Exodus 13:1-3

The LORD spoke to Moses, saying, “Sanctify to Me [that is, set apart for My purpose] every firstborn, the first offspring of every womb among the children of Israel, both of man and of animal; it is Mine.” Moses said to the people, “Remember [solemnly observe and commemorate] this day on which you came out of Egypt, out of the house of bondage and slavery; for by a strong and powerful hand the LORD brought you out of this place. And nothing leavened shall be eaten.