Exodus 12:42
It is a watch-night before the Lord who took them out of the land of Egypt: this same night is a watch-night to the Lord for all the children of Israel, through all their generations.
Deuteronomy 16:1-6
Take note of the month of Abib and keep the Passover to the Lord your God: for in the month of Abib the Lord your God took you out of Egypt by night.
Exodus 12:14
And this day is to be kept in your memories: you are to keep it as a feast to the Lord through all your generations, as an order for ever.
Exodus 13:10
So let this order be kept, at the right time, from year to year.