You shall eat no leavened bread with it. Seven days you shall eat it with unleavened bread, the bread of affliction—for you came out of the land of Egypt in haste—that all the days of your life you may remember the day when you came out of the land of Egypt.
Deuteronomy 16:3 Thou shalt eat no leavened bread with it. Because by this sign they were reminded of their having escaped in haste, as it were from the very flames; therefore does Moses so often enforce the prohibition of leaven.
Much of the communion between God and his people Israel was kept up, and a face of religion preserved in the nation, by the three yearly feasts, the institution of which, and the laws concerning them, we have several times met with already; and here they are repeated. I.
Commenting on Deuteronomy 16:1-17
Thou shalt eat no leavened bread with it,.... With the passover, as the Targum of Jonathan expresses it; that is, with the passover lamb, nor indeed with any of the passover, or peace offerings, as follows; see Exo 12:8. seven days shall ye eat unleavened bread therewith; with the passover; this plainly shows, that by the passover in the preceding verse is not meant strictly...