Leviticus 27:26-27 - Redemption Of The Firstborn
26 Only the firstling among beasts, which is made a firstling to Jehovah, no man shall sanctify it; whether it be ox or sheep, it is Jehovah's. 27 And if it be of an unclean beast, then he shall ransom it according to thine estimation, and shall add unto it the fifth part thereof: or if it be not redeemed, then it shall be sold according to thy estimation.
40 And Jehovah said unto Moses, Number all the first-born males of the children of Israel from a month old and upward, and take the number of their names. 41 And thou shalt take the Levites for me (I am Jehovah) 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 Jehovah commanded him, all the first-born among the children of Israel. 43 And all the first-born males according to 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 threescore and thirteen.
44 And Jehovah spake unto 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 Jehovah.
46 And for the redemption of the two hundred and threescore and thirteen of the first-born of the children of Israel, that are over and above the number of the Levites, 47 thou shalt take five shekels apiece by the poll; after the shekel of the sanctuary shalt thou take them (the shekel is twenty gerahs): 48 and thou shalt give the money, wherewith the odd number of them is redeemed, unto Aaron and to his sons.
49 And Moses took the redemption-money from them that were over and above them that were redeemed by the Levites; 50 from the first-born of the children of Israel took he the money, a thousand three hundred and threescore and five'shekels , after the shekel of the sanctuary: 51 and Moses gave the redemption-money unto Aaron and to his sons, according to the word of Jehovah, as Jehovah commanded Moses.