Numbers 18:15

Everything that opens the womb in all flesh, which they bring to Jehovah, of men or animals, shall be yours. Nevertheless, the first-born of man you shall surely redeem, and the first-born of unclean animals you shall redeem.

Exodus 34:20

But the firstling of an ass you shall redeem with a lamb. And if you do not redeem it, then you shall break its neck. All the first-born of your sons you shall redeem. And none shall appear before Me empty.

Exodus 13:2

Sanctify all the first-born to Me, whatever opens the womb among the sons of Israel, of man and of beast. It is Mine.

Exodus 13:12-13

you shall set apart to Jehovah every one that opens the womb, and every first-born that comes of any animal which you have; the males shall be Jehovah's.

Exodus 22:29

You shall not delay giving the fullness of your crops and juices of your vintage. You shall give the first-born of your sons to Me.

Leviticus 27:26-27

However, the first-born of an animal, which should be Jehovah's first-born, no man shall sanctify it, whether an ox, or sheep, it is Jehovah's.

Numbers 3:13

Because all the first-born are Mine. On the day that I struck all the first-born in the land of Egypt I set apart to Myself all the first-born in Israel, both man and animal. They shall be Mine. I am Jehovah.

Numbers 3:46

And for those that are to be redeemed of the two hundred and seventy-three of the first-born 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 first-born of an ass you shall redeem with a lamb. And if you will not redeem it, then you shall break its neck. And all the first-born of man among your sons you shall redeem.
Exodus 34:20
But the firstling of an ass you shall redeem with a lamb. And if you do not redeem it, then you shall break its neck. All the first-born of your sons you shall redeem. And none shall appear before Me empty.
Leviticus 27:27
And if it is of an unclean animal, then he shall redeem it according to your estimation, and shall add a fifth part of it to it. Or if it is not redeemed, then it shall be sold according to your estimation.

General references

Numbers 3:15
Number the sons of Levi according to their fathers' house, by their families. You shall number them, every male from a month old and upward.