Passover is Kept in its Appointed Season

Exodus 13:8 And thou shall show thy son in that day, saying, This is done because of that which the LORD did unto me when I came forth out of Egypt.

Exodus 13:9 And it shall be for a sign unto thee upon thine hand, and for a memorial between thine eyes, that the LORD'S law may be in thy mouth: for with a strong hand hath the LORD brought thee out of Egypt.

Exodus 13:10 Thou shalt therefore keep this ordinance in his season from year to year.