Luke 2:23

23.As it is written in the Law This was another exercise of piety which was discharged by Joseph and Mary. The Lord commanded, that all the males should be dedicated to him, in remembrance of their deliverance; because when the angel slew all the first-born of Egypt, (Exodus 12:29,) he had spared the first-born of Israel.

“On the day that I smote all the first-born in the land of Egypt, I hallowed unto me all the first-born in Israel, both man and beast: mine shall they be:
I am the Lord” (Numbers 3:13.)

They were afterwards permitted to redeem their first-born at a certain price. Such was the ancient ceremony: and, as the Lord is the common Redeemer of all, (193) he has a right to claim us as his own, from the least to the greatest. Nor is it without a good reason, that Luke so frequently repeats the statement, that Joseph and Mary did what was written in the law of the Lord For these words teach us, that we must not, at our own suggestion, attempt any thing in the worship of God, but must obediently follow what he requires in his Word.