Care is here taken to perpetuate the remembrance,
I. Of the preservation of Israel's firstborn, when the firstborn of the Egyptians were slain. In memory of that distinguishing favour, and in gratitude for it, the firstborn, in all ages, were to be consecrated to God, as his peculiars (Exo 13:2), and to be redeemed, Exo 13:13. God, who by the right of creation is proprietor and sovereign of all the creatures, here lays claim in particular to the firstborn of the Israelites, by right of protection: Sanctify to me all the firstborn. The parents were not to look upon themselves as interested in their firstborn, till they had first solemnly presented them to God, recognized his title to them, and received them back, at a certain rate, from him again. Note, 1. That which is by special distinguishing mercy spared to us should be in a peculiar manner dedicated to God's honour; at least some grateful acknowledgment, in works of piety and charity, should be made, when our lives, or the lives of our children, have been given us for a prey. 2. God, who is the first and best, should have the first and best, and to him we should resign that which is most dear to us, and most valuable. The firstborn were the joy and hope of their families. Therefore they shall be mine, says God. By this is will appear that we love God best (as we ought) if we are willing to part with that to him which we love best in this world. 3. It is the church of the firstborn that is sanctified to God, Heb 12:23. Christ it the firstborn among many brethren (Rom 8:29), and, by virtue of their union with him, all that are born again, and born from above, are accounted as firstborn. There is an excellency of dignity and power belonging to them; and, if children, then heirs.
II. The remembrance of their coming out of Egypt must also be perpetuated: "Remember this day, Exo 13:3. Remember it by a good token, as the most remarkable day of your lives, the birthday of your nation, or the day of its coming of age, to be no longer under the rod." Thus the day of Christ's resurrection is to be remembered, for in it we were raised up with Christ out of death's house of bondage. The scripture tells us not expressly what day of the year Christ rose (as Moses told the Israelites what day of the year they were brought out of Egypt, that they might remember it yearly), but very particularly what day of the week it was, plainly intimating that, as the more valuable deliverance, and of greater importance, it should be remembered weekly. Remember it, for by strength of hand the Lord brought you out. Note, The more of God and his power appears in any deliverance, the more memorable it is. Now, that it might be remembered,
1. They must be sure to keep the feast of unleavened bread, Exo 13:5-7. It was not enough that they remembered it, but they must celebrate the memorial of it in that way which God had appointed, and use the instituted means of preserving the remembrance of it. So, under the gospel, we must not only remember Christ, but do this in remembrance of him. Observe, How strict the prohibition of leaven is (Exo 13:7); not only no leaven must be eaten, but none must be seen, no, not in all their quarters. Accordingly, the Jews' usage was, before the feast of the passover, to cast all the leavened bread out of their houses: they burnt it, or buried it, or broke it small and scattered it in the wind; they searched diligently with lighted candles in all the corners of their houses, lest any leaven should remain. The care and strictness enjoined in this matter were designed, (1.) To make the feast the more solemn, and consequently the more taken notice of by their children, who would ask, "Why is so much ado made?" (2.) To teach us how solicitous we should be to put away from us all sin, Co1 5:7.
2. They must instruct their children in the meaning of it, and relate to them the story of their deliverance out of Egypt, Exo 13:8. Note, (1.) Care must be taken betimes to instruct children in the knowledge of God. Here is an ancient law for catechising. (2.) It is particularly of great use to acquaint children betimes with the stories of the scripture, and to make them familiar to them. (3.) It is a debt we owe to the honour of God, and to the benefit of our children's souls, to tell them of the great works God has done for his church, both those which we have seen with our eyes done in our day and which we have heard with our ears and our fathers have told us: Thou shalt show thy son in that day (the day of the feast) these things. When they were celebrating the ordinance, they must explain it. Every thing is beautiful in its season. The passover is appointed for a sign, and for a memorial, that the Lord's law may be in thy mouth. Note, We must retain the remembrance of God's works, that we may remain under the influence of God's law. And those that have God's law in their heart should have it in their mouth, and be often speaking of it, the more to affect themselves and to instruct others.

When the Lord shall bring thee into the land - Hence it is pretty evident that the Israelites were not obliged to celebrate the Passover, or keep the feast of unleavened bread, till they were brought into the promised land.

And it shall be when the Lord shall bring thee into the land of the Canaanites,.... Though the whole land was called the land of Canaan, yet there was one tribe or nation of them particularly so called as here, distinct from those that follow:

and the Hittites, and the Amorites, and the Hivites, and the Jebusites; there were seven nations in all, but two are here omitted, the Girgashites and Perizzites, but they are added in the Septuagint version, see Deu 7:1.

which he swore unto thy fathers to give thee; to Abraham, Isaac, and Jacob; so that they might be assured they would be brought into it, since they had both the word and oath of God for it; and which is the rather mentioned now for their encouragement, since they were at this time set forward in their journey thitherwards:

a land flowing with milk and honey; See Gill on Exo 3:8,

that thou shalt keep this service in this month; the month of Abib; that is, the following service concerning unleavened bread; it is concluded from hence by some, that those laws concerning the passover, and eating unleavened bread, and sanctifying the firstborn, did not oblige the Israelites, while in the wilderness, only when they came into the land of Canaan; and it seems pretty clear that this was the case with respect to the two latter, but not the former, since it is certain they did keep the passover in the wilderness, and were obliged to it, Num 9:1 but then it may be observed, that there is no mention there of their keeping the feast of unleavened bread, only of the passover, as here no mention is made of the feast of the passover, which, though they followed one another, were, two distinct feasts.

when the Lord shall bring thee--The passover is here instituted as a permanent festival of the Israelites. It was, however, only a prospective observance; we read of only one celebration of the passover during the protracted sojourn in the wilderness [Num 9:5]; but on their settlement in the promised land, the season was hallowed as a sacred anniversary [Jos 5:10], in conformity with the directions here given.