Numbers 8:17-19

Douay-Rheims 1899 American Edition

¹⁷ For all the firstborn of the children of Israel, both of men and of beasts, are mine. From the day that I slew every firstborn in the land of Egypt, have I sanctified them to myself:

¹⁸ And I have taken the Levites for all the firstborn of the children of Israel:

¹⁹ And have delivered them for a gift to Aaron and his sons out of the midst of the people, to serve me for Israel in the tabernacle of the covenant, and to pray for them, lest there should be a plague among the people, if they should presume to approach unto my sanctuary.