Exodus 34:19-23

All that openeth the matrix is mine; and every firstling among thy cattle, whether ox or sheep, that is male.

But the firstling of an ass thou shalt redeem with a lamb: and if thou redeem him not, then shalt thou break his neck. All the firstborn of thy sons thou shalt redeem. And none shall appear before me empty.

Six days thou shalt work, but on the seventh day thou shalt rest: in earing time and in harvest thou shalt rest.

And thou shalt observe the feast of weeks, of the firstfruits of wheat harvest, and the feast of ingathering at the year’s end.

Thrice in the year shall all your men children appear before the Lord GOD, the God of Israel.