Numbers 3:13 WBT

¹¹  And the LORD spoke to Moses, saying,

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

¹³  Because all the first-born [are] mine; [for] on the day that I smote all the first-born in the land of Egypt, I hallowed to me all the first-born in Israel, both man and beast: mine they shall be: I [am] the LORD.

¹⁴  And the LORD spoke to 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.