Exodus 34:18

The feast of unleavened bread shalt thou keep
Which was instituted at the time of their coming out of Egypt, and on that account, and then observed, ( Exodus 12:15 Exodus 12:18 Exodus 12:19 ) ( Exodus 13:6 Exodus 13:7 ) and afterwards repeated, and the month expressed in which they were to keep it, and the reason of it, as it here follows, (See Gill on Exodus 13:15).