Note: It should be noted that John Gill believed that Sunday is "the Christian Sabbath" and "the Lord's Day", and that it was the appropriate day for worship. However, he did not accept the view, popular among Sabbatarians, that the Sabbath was a "creation ordinance", i.e. that it was instituted during the creation week.  Gill's arguments against the "creation ordinance" theory are so compelling that I felt it valuable to provide them here.

... But the circumstance of "time", or a stated day of worship, requires more particular consideration; it having been a matter of controversy which has exercised the minds of good and learned men, for a century or two past, and not yet decided to the satisfaction of all parties; and in order to obtain what satisfaction we can, it will be proper to inquire,

1. What day has been, or is observed, as a stated time of public worship; with the reasons thereof. And,
 
1a. First, it has been thought and asserted, that the seventh day from the creation was enjoined Adam in a state of innocence, as a day of public and religious worship, and so to be observed by his posterity in after times; but if it was enjoined Adam in his state of innocence, it must be either by the law of nature, written on his heart, or by a positive law given him.

1a1. First, it does not seem to be the law of nature written on his heart; for then,

1a1a. He must be bound to keep a Sabbath before the institution of it; he was created on the sixth day, after the image of God; one part of which was the law of nature, written on his heart; but the institution of the Sabbath day was not until the seventh day, if it was then; for it is yet a matter of question.

1a1b. There would have been some remains of it in his posterity after the fall; and even among the Gentiles, for these have the "law written in their hearts", Ro 2:14 but now it does not appear that they were ever directed by the law and light of nature to observe the seventh day of the week as an holy Sabbath; what has been alleged in favour of it will be considered hereafter.

1a1c. Was this the case, it would have been reinscribed with other laws in more legible characters on the hearts of God's people in regeneration, according to the promise in the covenant of grace, Heb 8:10 and had the law of the seventh day Sabbath been one of them, it must easily have been discerned by them; and the observance of it would have been out of question. Nor,

1a2. Secondly, does it seem to be enjoined Adam, by any positive law; and, indeed, if it had been written on his heart, as a branch of the law of nature, there would have been no need of any such law to have directed and instructed him; and to have a positive law given him, to keep a seventh day Sabbath, without any positive rules and directions what worship should be observed by him on that day, which do not appear, the law would have been useless; we have no account of any positive law given to Adam in a state of innocence, but that which forbad eating of the tree of knowledge of good and evil; which tree, and its fruit, we know nothing of; and did we, that law would not be binding upon us. The proof of such a law, with respect to the Sabbath, is founded,

1a2a. On Ge 2:2,3 where it is said, that God having ended his work, "rested on the seventh day, and God blessed the seventh day and sanctified it". But,

1a2a1. No mention is made of a Sabbath, and of the sanctification of that, as in the fourth command, Ex 20:11 only of the seventh day, and not of that as a Sabbath.

1a2a2. The words are a narrative of what God did himself; but do not contain a precept of what Adam should do; they only declare what God did, that he blessed and sanctified the seventh day; but do not enjoin Adam to keep it holy, as a Sabbath.

1a2a3. At most they seem only to design a destination of that day to holy service hereafter; God "blessed" it, that is, pronounced it an happy day; all his works being finished, and man, an holy creature, the crown and glory of all, made after his image {2}: on a survey of which, God rested, and took delight, pleasure, and refreshment in them, on the seventh day; which he "sanctified", not by keeping it holy himself, nor by imparting any holiness to it, which a day is not capable of; but he separated, or set it apart for holy use in after time, which is a very common sense of this word: so Jeremiah was sanctified before he was born; that is, appointed and ordained to be a holy prophet; which purpose was not carried into execution until some time after; and so God might be said to sanctify or set apart in his mind and purpose the seventh day to be an holy Sabbath in future time; though it was not actually executed, as it should seem by what will be hereafter observed, until many hundred years after the creation. Besides,

1a2a4. The words in Ge 2:2,3, are understood by many learned men proleptically, or by way of anticipation; as other things are in this same chapter; so some places are called by the names they bore in the times of Moses, which they had not from the beginning; see Ge 2:11-14 or the words may be considered as in a parenthesis; and the rather, since had they been read, or to be read, in common with the preceding, the word "God", and the phrase the "seventh day", would have been omitted; and have been read, "and he blessed and sanctified it"; and the reason for it, which follows, seems manifestly taken from the fourth command, as given on Mount Sinai, Ex 20:11 and Moses writing his history of the creation, after this precept was given, took the opportunity of inserting this whole passage, to give the greater sanction to it with the Israelites.

1a2a5. After all, be it that the text in Genesis enjoins the keeping the seventh day from the creation as a Sabbath; which seventh day now cannot be known by any people or persons whatever, it could never be the same with the Jewish seventh day Sabbath; for that was to be observed after six days labour of man; "Six days shalt thou labour", &c. whereas this could be only after the six days labour of God, who rested from his work on the seventh; but it was Adam's first day, and could not with any propriety be called a rest from labour to him, when, as yet, he had not laboured at all: such a Sabbath was not suitable to him in a state of innocence, which supposes imperfection and sin; the creature would not have been in bondage had he not sinned, this was the effect of the fall; Adam, in innocence, had no manservant nor maidservant, nor any cattle in a state of bondage, groaning under burdens, to rest from their labours. This is a law merely calculated for sinful man.

1a2b. The other remaining proof of such a law so early is taken from Heb 4:3,4 where no mention is made of a seventh day Sabbath; and in which the apostle takes notice of the several rests which had been under the former dispensation, and shows, that neither of them was the rest promised, and had, under the gospel dispensation: not the seventh day rest from the creation, for that was God's rest: not the rest of the Israelites in the land of Canaan, which Joshua gave them; for then David, a long time after, would not have spoken of another day of rest, the gospel dispensation, into which believers now enter. Upon the whole, it must appear at least very dubious and uncertain, that there was any institution of a seventh day Sabbath from the creation; and especially when it is considered,
 
 

1b. Secondly, that there is no proof of the patriarchs from Adam to the times of Moses observing such a day. For,
 
1b1. We no where read of any law being given them for the observation of the seventh day Sabbath; Adam and Eve had a law which forbid the eating of the fruit of the tree of knowledge; which Tertullian calls the primordial law; Abel was taught the law of sacrifices; Noah had the laws which forbid eating the blood with the flesh of a beast alive, and the shedding of human blood; and Abraham the law of circumcision; but neither of them had any law, as we know of, which enjoined them to observe the seventh day Sabbath. The Jews pretend that there were seven laws given to the sons of Noah; but this of keeping the seventh day Sabbath is not among them.

1b2. Many of the religious actions of the patriarchs are taken notice of, and commended, both ceremonial and moral; as their offering of sacrifice, calling on the name of the Lord, prayer to God, and meditation on him and his works their piety, fear of God, and eschewing evil; but not a word of their observance of a seventh day Sabbath.

1b3. The sins of men, both before and after the flood, are observed, but Sabbath breaking does not appear among them. The old world was full of violence, rapine, and oppression; and in the new world, intemperance, incest, idolatry, and other sins, men were chargeable with; but not with this: it does not appear among the sins of Sodom and Gomorrah; nor is it to be found among the abominations for which the old inhabitants of Canaan were cast out of it. But no sooner was the law of the Sabbath given to the Israelites in the wilderness, but we hear of the breach of it, and of a severe punishment of it.

1b4. It was the general opinion of the ancient fathers of the Christian church, that the patriarchs did not observe a Sabbath, nor were obliged to it; but were righteous men, and saved without it: not Adam, nor Abel, nor Enock, nor Noah, nor Melchizedek, nor Lot, nor Abraham, nor Job, nor any before Moses; so say Justin Martyr {3}, Irenaeus {4}, Tertullian {5}, and Eusebius {6}; by whom are mentioned particularly all the above persons, as good men, and non-observers of a Sabbath. Some have fancied that they have found instances of a seventh day Sabbath observed in the time of the patriarchs; as at the offerings of Cain and Abel, which ate said to be "in process of time", or "at the end of days", Ge 4:3 but this phrase seems to design, not the end of a week, or seven days, no number being expressed, but rather the end of a year, days being sometimes put for a year {7}; and so refers to the harvest, at the end of the year, when the fruits of the earth were gathered in; and therefore Cain might think his sacrifice, at that time, would have been the more acceptable. And some conjecture a Sabbath was observed by Noah, in the ark, Ge 8:10,12 since he is said to send out the dove again after seven days; but this number seven has respect, not to the first day of the week, from whence the days were numbered; but the first sending out of the dove, be it on what day it may. And besides, Noah might have respect to the known course of the moon, which puts on another face every seven days {8}; and which, in its increase and wane, might have an influence upon the water, which he was careful to observe and make trial of this way. Moreover, it is observed, that in Job's time there was a day when the sons of God met together, Job 1:62:1 but who these sons of God were, whether angels or men, is not certain; nor where, nor on what day they met; no mention is made of a seventh day, much less of a Sabbath; nor of a certain rotation of this day every week; nor of the distance between the first and second meeting. Arguments from this, and the above instances, must be very farfetched, and are very slight and slender grounds to build such an hypothesis upon, as the observation of a seventh day Sabbath.
 
 

1c. Thirdly, there is no mention of a Sabbath before the descent of the manna in the wilderness of Sin: some of the Jewish writers {9} speak of it as given at Marah, a few weeks before, which they suppose is included in the word "statute", Ex 15:25 but this is said without any foundation; but the seventh day from the descent of the manna is expressly called a "Sabbath", Ex 16:23-26 and is the first we hear of, and which appears to be quite a new thing; for had the Israelites been used to a seventh day Sabbath, the rulers of the people might easily have conjectured, that the reason of twice as much bread being gathered on the sixth day, was on the account of the Sabbath being the day following, as a provision for that, had that been the case, without coming to tell Moses of it, who gave this as a reason of it to them; "Tomorrow is", or rather it should be supplied, "shall be, the rest of the holy Sabbath to the Lord"; for a "tomorrow" cannot be spoken of with propriety in the present tense, "is"; but as future, "shall be"; and therefore on the seventh day, when the manna ceased, which was a confirmation of it, he says to them, "see", take notice of it, as something new and wonderful, and a sufficient reason of the institution of the Sabbath, and why that day was given unto them for a Sabbath; and when the fourth command was given, a month after, it is introduced with a "memento", as the other commands are not; "Remember", what had been lately enjoined them; and that appears to be a new law; for when a man was found the breach of it, no penalty being as yet people brought him to Moses, and he was put into the ward, until the mind of God was known concerning it, Nu 15:31-36. Moreover, if there had been a Sabbath before the giving of the manna, the Sabbath preceding the seventh day from the descent of that, must have been the fifteenth of the month, on which day it is certain the Jews had a wearisome journey, by divine appointment, the cloud going before them, Ex 16:1 and was concluded with gathering quails; so that it was not a day of rest to them, nor the rest of the holy Sabbath to the Lord.
 

1d. Fourthly, the seventh day Sabbath, as it was declared on the descent of the manna, that it was peculiar to the Jews; "The Lord hath given you the Sabbath; --so the people rested the seventh day", Ex 16:29,30. So it was when it received a further sanction from the fourth precept of the decalogue. For,
 

1d1. The whole decalogue, or ten commands of the law of Moses, as such, were given to the Jews only {10}; as a covenant, it was made with the Israelites in the wilderness, and not even with their fathers, which were before them; and in which respect they had the preference to all other nations on earth, as Moses affirms, De 5:2-21 4:6-8 and as is affirmed by David, Ps 147:19,20 and by the apostle Paul, Ro 9:4 and which appears from the preface to the decalogue; "I am the Lord thy God, which brought thee out of the land of Egypt"; which cannot be said of any other nation.

1d2. The fourth command is particularly and expressly declared as peculiar to them; "My Sabbaths shall ye keep", saith the Lord; "for it is a sign between me and you", and not others, Ex 31:13 that is, of the national covenant between them. The same is repeated, Ex 31:16,17 where the children of Israel, as distinct from all other nations to whom it was no sign, are directed to keep the Sabbath. So Nehemiah says, that when God spoke to the Israelites in the wilderness, he made "known to them his holy Sabbath"; which it seems had not been made known unto them before; but now was made known to them, and not to others; and is mentioned along with peculiar precepts, statutes, and laws commanded them, Ne 9:14 and the prophet Ezekiel, from the Lord, tells the Jews, that the Lord had "given", to their fathers in the wilderness, his "Sabbaths, to be a sign between him and them"; it is not said he restored them, but "gave" them, denoting a new institution, and as peculiarly belonging to them: and this is the sense of the Jewish nation in general {11}, that the Sabbath only belongs to them, and that the Gentiles are not obliged to keep it; for though a Gentile proselyte or stranger within the gate, for the sake of national decorum, and to avoid offence and scandal, was to do no work on it for an Israelite, yet he might for himself, as the Jews interpret it {12}; but then this supposes, that a stranger not within the gate, was not obliged to observe it. Besides, some of the Jewish writers understand this stranger, or proselyte, of a proselyte of righteousness, who was under equal obligation to the commands of the law as a Jew.

1d3. The time and place when and where this precept was given, with the reason of it, show that it was peculiar to the Jews; it was given them in the wilderness, after they were come out of Egypt; and their deliverance from thence is expressly observed, as the reason why it was commanded them, De 5:15. The Lord's resting on the seventh day from his works of creation, is used as an argument to enforce the keeping of the seventh day Sabbath, now enjoined; but not as a reason of the institution of it.

1d4. None but Jews were ever charged with the breach of the seventh day Sabbath; the children of Israel were charged with it in the wilderness, soon after it was enjoined them, Eze 20:20,21,23,24 so in Nehemiah's time, though the Tyrians, who sold fish to the Jews on Sabbath days, were threatened, and shut out of the city, and forbid to come there with their goods; yet it was the Jews who bought them, who are charged with the profanation of the Sabbath, Ne 13:15-20 and it was the sense of the Jews, that the Gentiles are not to be punished for the breach of it; yea, rather, that they are punishable for keeping it {13}; they having no other laws binding upon them: but the seven laws they speak of, as given to the sons of Noah.

1d5. The law of observing the seventh day Sabbath is not of a moral nature; was it, it would be binding on all mankind, Jews and Gentiles; and could not have been dispensed with, nor abolished, as it is, Mt 12:1-12Col 2:16,17 and if such, as has been observed, it must have been written on the heart of Adam, when created; and would be, not only reinscribed on the hearts of regenerate men, but even the work of it would appear to be written on the hearts of Gentiles, as their consciences would bear witness; whereas it does not appear. Some, indeed, pretend to say, that the seventh day of the week was reckoned holy with the Gentiles; but of all the instances produced from Clemens and Eusebius, there is but one now extant among the poets, and that is in Hesiod; and the seventh day he speaks of as holy, is not the seventh day of the week, but the seventh day of the month, the birthday of Apollo, as the poet himself suggests, and the Scholiasts {14} on him; which was the seventh day of the month Thargelion, kept sacred at Athens on that account; hence Apollo was called Ebdomegena {15}. As for the Jews' seventh day Sabbath, the Heathen writers {16} speak of it as having its origin from Moses, and as peculiar to the Jews {17}, and the day itself was held by them in the utmost contempt; see La 1:7 there is scarce a poet of theirs {18} but has a lash at it, and at the Jews on account of it; and represent them as a parcel of idle people, who keep that day to indulge themselves in sloth; the principal day of the week sacred with the Gentiles, was the first day of the week, dedicated to the sun, and from thence called Sunday: so that if any argument can be drawn from the observation of the heathens, it is in favour of the Christian, and not of the Jewish Sabbath. ...