Numbers 3:10-15

King James Version

¹⁰ And thou shalt appoint Aaron and his sons, and they shall wait on their priest's office: and the stranger that cometh nigh shall be put to death.

¹¹ And the Lord spake unto Moses, saying,

¹² And I, behold, I have taken the Levites from among the children of Israel instead of all the firstborn that openeth the matrix among the children of Israel: therefore the Levites shall be mine;

¹³ Because all the firstborn are mine; for on the day that I smote all the firstborn in the land of Egypt I hallowed unto me all the firstborn in Israel, both man and beast: mine shall they be: I am the Lord.

¹⁴ And the Lord spake unto Moses in the wilderness of Sinai, saying,

¹⁵ Number the children of Levi after the house of their fathers, by their families: every male from a month old and upward shalt thou number them.