Exodus 34:18-20

34:18 “You must keep the Feast of Unleavened Bread. For seven days you must eat bread made without yeast, as I commanded you; do this at the appointed time of the month Abib, for in the month Abib you came out of Egypt.

34:19 “Every firstborn of the womb belongs to me, even every firstborn of your cattle that is a male, whether ox or sheep. 34:20 Now the firstling of a donkey you may redeem with a lamb, but if you do not redeem it, then break its neck. You must redeem all the firstborn of your sons.

“No one will appear before me empty-handed.