Numbers 3:12,40-43
And I, behold, I have taken the Levites from among the children of Israel instead of all the firstborn that opens the matrix among the children of Israel: therefore the Levites shall be mine;
Torrey's Topical Textbook—AKJV

Numbers 8:18
And I have taken the Levites for all the firstborn of the children of Israel.
Torrey's Topical Textbook—AKJV