Exodus 34:18-22

“You shall keep the Feast of Unleavened Bread. For seven days you are to eat unleavened bread, as I commanded you, at the appointed time in the month of Abib; for in the month of Abib you came out of Egypt.

“The firstborn from every womb belongs to Me, and all your male livestock, the firstborn from cattle and sheep.

You shall redeem with a lamb the firstborn from a donkey; and if you do not redeem it, then you shall break its neck. You shall redeem all the firstborn of your sons. None are to appear before Me empty-handed.

“You shall work six days, but on the seventh day you shall rest; even during plowing time and harvest you shall rest.

And you shall celebrate the Feast of Weeks, that is, the first fruits of the wheat harvest, and the Feast of Ingathering at the turn of the year.