Exodus 34:18-23

¹⁸"The feast of unleavened bread you shall keep. Seven days you shall eat unleavened bread, as I commanded you, at the time appointed in the month Abib; for in the month Abib you came out from Egypt. ¹⁹All that opens the womb is mine, all your male cattle, the firstlings of cow and sheep. ²⁰The firstling of an ass you shall redeem with a lamb, or if you will not redeem it you shall break its neck. All the first-born of your sons you shall redeem. And none shall appear before me empty.

²¹"Six days you shall work, but on the seventh day you shall rest; in plowing time and in harvest you shall rest. ²²And you shall observe the feast of weeks, the first fruits of wheat harvest, and the feast of ingathering at the year's end. ²³Three times in the year shall all your males appear before the LORD God, the God of Israel.