Numbers 18:15

Every thing that opens the womb in all flesh, which they shall offer unto the LORD, whether it is of men or animals, shall be thine; nevertheless the firstborn of man shalt thou surely ransom, and the firstborn of unclean animals shalt thou ransom.

Exodus 34:20

But the firstborn of an ass thou shalt ransom with a lamb, and if thou ransom him not, then shalt thou cut off his head. All the firstborn of thy sons thou shalt ransom, and none shall appear before me empty.

Exodus 13:2

Sanctify unto me all the firstborn, whatever opens the womb among the sons of Israel, both of man and of beast; for it is mine.

Exodus 13:12-13

that thou shalt set apart unto the LORD all that opens the womb and in the same manner every firstborn that opens the wombs of thy animals; the males shall be the LORD's.

Exodus 22:29

Thou shalt not delay to offer the first of thy ripe fruits and of thy liquors; the firstborn of thy sons shalt thou give unto me.

Leviticus 27:26-27

But the firstborn of the animals, which because it is firstborn belongs to the LORD, no one shall sanctify it; whether it is ox or sheep, it is the LORD's.

Numbers 3:13

because all the firstborn are mine; from the day that I smote all the firstborn in the land of Egypt, I sanctified unto me all the firstborn in Israel, both of men and of animals; they shall be mine: I am the LORD.

Numbers 3:46

And for the ransoms of the two hundred seventy-three of the firstborn of the sons of Israel, who are more than the Levites,

Treasury of Scripture Knowledge

Summary

Every thing that openeth the matrix in all flesh, which they bring unto the LORD, whether it be of men or beasts, shall be thine: nevertheless the firstborn of man shalt thou surely redeem, and the firstling of unclean beasts shalt thou redeem.

General references

Bible References

The firstborn

Exodus 13:13
And every firstborn of an ass thou shalt ransom with a lamb; and if thou wilt not ransom it, then thou shalt cut off its head; and in the same manner thou shalt ransom all the human firstborn among thy sons.
Exodus 34:20
But the firstborn of an ass thou shalt ransom with a lamb, and if thou ransom him not, then shalt thou cut off his head. All the firstborn of thy sons thou shalt ransom, and none shall appear before me empty.
Leviticus 27:27
And if it is of an unclean beast, it shall be ransomed according to thy estimation, and they shall add a fifth part unto it; or if it is not redeemed, then it shall be sold according to thy estimation.

General references

Numbers 3:15
Number the sons of Levi by the houses of their fathers, by their families; thou shalt number every male from a month old and upward.