Exodus 12:42
It was a night of vigil for the Lord to bring them out from the land of Egypt, and so on this night all Israel is to keep the vigil to the Lord for generations to come.
Deuteronomy 16:1-6
Observe the month Abib and keep the Passover to the Lord your God, for in that month he brought you out of Egypt by night.
Exodus 12:14
This day will become a memorial for you, and you will celebrate it as a festival to the Lord -- you will celebrate it perpetually as a lasting ordinance.
Exodus 13:10
So you must keep this ordinance at its appointed time from year to year.