15 Every thing that opens the womb in all flesh, which they bring unto the LORD, whether it be of men or beasts, shall be yours: nevertheless the firstborn of man shall you surely redeem, and the first born of unclean beasts shall you redeem.
Numbers 18:15 Cross References - UKJV
Exodus 13:2
2 Sanctify unto me all the firstborn, whatsoever opens the womb among the children of Israel, both of man and of beast: it is mine.
Exodus 13:12-13
12 That you shall set apart unto the LORD all that opens the womb, and every first born that comes of a beast which you have; the males shall be the LORD's.
13 And every first born of an ass you shall redeem with a lamb; and if you will not redeem it, then you shall break his neck: and all the firstborn of man among your children shall you redeem.
Exodus 22:29
29 You shall not delay to offer the first of your ripe fruits, and of your liquors: the firstborn of your sons shall you give unto me.
Exodus 34:20
20 But the first born of an ass you shall redeem with a lamb: and if you redeem him not, then shall you break his neck. All the firstborn of your sons you shall redeem. And none shall appear before me empty.
Leviticus 27:26-27
26 Only the first born of the beasts, which should be the LORD's first born, no man shall sanctify it; whether it be ox, or sheep: it is the LORD's.
27 And if it be of an unclean beast, then he shall redeem it according to your estimation, and shall add a fifth part of it thereto: or if it be not redeemed, then it shall be sold according to your estimation.
Numbers 3:13
13 Because all the firstborn are mine; for on the day that I stroke all the firstborn in the land of Egypt I hallowed unto me all the firstborn in Israel, both man and beast: mine shall they be: I am the LORD.
Numbers 3:46
46 And for those that are to be redeemed of the two hundred and threescore and thirteen of the firstborn of the children of Israel, which are more than the Levites;