Exodus 23:15
23:15 You are to observe the Feast of Unleavened Bread; seven days you must eat bread made without yeast, as I commanded you, at the appointed time of the month of Abib, for at that time you came out of Egypt. No one may appear before me empty-handed.
Exodus 34:20
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.