Exodus 12:42
It is a night to be much observed unto Jehovah for bringing them out from the land of Egypt: this is that night of Jehovah, to be much observed of all the children of Israel throughout their generations.
Deuteronomy 16:1-6
Observe the month of Abib, and keep the passover unto Jehovah thy God; for in the month of Abib Jehovah thy God brought thee forth out of Egypt by night.
Exodus 12:14
And this day shall be unto you for a memorial, and ye shall keep it a feast to Jehovah: throughout your generations ye shall keep it a feast by an ordinance for ever.
Exodus 13:10
Thou shalt therefore keep this ordinance in its season from year to year.