Exodus 13:2

Sanctify unto me every first-born. Sanctification in this place means, that the first-born males of the Hebrews should be deputed to the ministry in the divine worship: and the first-born of beasts to be given for a sacrifice. (Challoner) --- Sanctify, set apart. (Menochius) --- Openeth, the first male fruit of the womb. If a female was born the first, none of the children were to be redeemed. (Luke ii. 23.) Jesus Christ submitted to this law; though many of the fathers have asserted that, on account of his miraculous conception and birth, he was not subjected to it; while others maintain the contrary. (Calmet)