Sanctify unto me all the firstborn, whatsoever openeth the womb among the children of Israel, both of man and of beast: it is mine.

Wesley's Notes

13:2 Sanctify to me all the first - born - The parents were not to look upon themselves as interested in their first - born, till they had first solemnly presented them to God, and received them back from him again. It is mine - By a special right, being by my singular favour preserved from the common destruction.

Jamieson-Fausset-Brown Bible Commentary

2. Sanctify unto me all the first-born-To "sanctify" means to "consecrate," to "set apart" from a common to a sacred use. The foundation of this duty rested on the fact that the Israelites, having had their first-born preserved by a distinguishing act of grace from the general destruction that overtook the families of the Egyptians, were bound in token of gratitude to consider them as the Lord's peculiar property (compare Heb 12:23).

Matthew Henry's Concise Commentary

13:1-10 In remembrance of the destruction of the first-born of Egypt, both of man and of beast, and the deliverance of the Israelites out of bondage, the first-born males of the Israelites were set apart to the Lord. By this was set before them, that their lives were preserved through the ransom of the atonement, which in due time was to be made for sin. They were also to consider their lives, thus ransomed from death, as now to be consecrated to the service of God. The parents were not to look upon themselves as having any right in their first-born, till they solemnly presented them to God, and allowed his title to them. That which is, by special mercy, spared to us, should be applied to God's honour; at least, some grateful acknowledgment, in works of piety and charity, should be made. The remembrance of their coming out of Egypt must be kept up every year. 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, but it states particularly what day of the week it was; as the more valuable deliverance, it should be remembered weekly. The Israelites must keep the feast of unleavened bread. Under the gospel, we must not only remember Christ, but observe his holy supper. Do this in remembrance of him. Also care must be taken to teach children the knowledge of God. Here is an old law for catechising. It is of great use to acquaint children betimes with the histories of the Bible. And those who have God's law in their heart should have it in their mouth, and often speak of it, to affect themselves, and to teach others.