Exodus 34:18-23

¹⁸The feast of unleavened bread shalt thou keep. Seven days thou shalt eat unleavened bread, as I commanded thee, in the time of the month Abib: for in the month Abib thou camest out from Egypt. ¹⁹All that openeth the matrix is mine; and every firstling among thy cattle, whether ox or sheep, that is male. ²⁰But 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.

²¹Six days thou shalt work, but on the seventh day thou shalt rest: in earing time and in harvest thou shalt rest. ²²And thou shalt observe the feast of weeks, of the firstfruits of wheat harvest, and the feast of ingathering at the year's end. ²³Thrice in the year shall all your men children appear before the Lord GOD, the God of Israel.