Exodus 13:1-4

Then the LORD said to Moses,

“Consecrate to Me every firstborn male. The firstborn from every womb among the Israelites belongs to Me, both of man and beast.”

So Moses told the people, “Remember this day, the day you came out of Egypt, out of the house of slavery; for the LORD brought you out of it by the strength of His hand. And nothing leavened shall be eaten.