Commentaries:
The implication is that, when Israel finally came into the land, God made it possible for them to come into it. In other words, it was because of what the Lord did, not only in Egypt, but also in the wilderness, that enabled them to reach and enter the land. It is what the Lord does.
This is not a minor bit of trivia. It is not merely that we come out of sin and this world, but this fact puts everything about our coming out—our growth and overcoming, and eventually entering the Kingdom of God—into its proper perspective, because human nature is ever ready to take the credit for more than it actually accomplishes.
John W. Ritenbaugh
Sanctification and Holiness (Part 1)
The word redeem means "buy back." If a family's firstborn donkey was critical to their livelihood, they could buy it back from God by offering a lamb in its place. Of course, God did not demand that His people offer their firstborn children as literal human sacrifices. They, too, were to be bought back by means of a lamb sacrifice.
Staff
The Law of the Firstborn