Numbers 3:44

41 And thou shalt take the Levites for me (I [am] the LORD) instead of all the first-born among the children of Israel; and the cattle of the Levites, instead of all the firstlings among the cattle of the children of Israel.

42 And Moses numbered, as the LORD commanded him, all the first-born among the children of Israel.

43 And all the first-born males by the number of names, from a month old and upward, of those that were numbered of them, were twenty and two thousand two hundred and seventy and three.

44 And the LORD spoke to Moses, saying,

45 Take the Levites instead of all the first-born among the children of Israel, and the cattle of the Levites instead of their cattle; and the Levites shall be mine: I [am] the LORD.

46 And for those that are to be redeemed of the two hundred and seventy and three, of the first-born of the children of Israel, which are more than the Levites:

47 Thou shalt even take five shekels apiece by the poll, after the shekel of the sanctuary shalt thou take [them]: the shekel [is] twenty gerahs.