Numbers 3:14

¹²Behold, I have taken the Levites from the midst of the children of Israel, instead of every male that opens the womb from among the children of Israel: they shall be their ransom, and the Levites shall be mine.

¹³For every firstborn is mine; in the day in which I smote every firstborn in the land of Egypt, I sanctified to myself every firstborn in Israel: both of man and beast, they shall be mine: I am the Lord.

— Numbers 3:14 —

¹⁵Take the number of the sons of Levi, according to the houses of their families, according to their divisions; number ye them every male from a month old and upward.

¹⁶And Moses and Aaron numbered them by the word of the Lord, as the Lord commanded them.