Thou shalt eat no leavened bread with it; seven days shalt thou eat unleavened bread therewith, even the bread of affliction; for thou camest forth out of the land of Egypt in haste: that thou mayest remember the day when thou camest forth out of the land of Egypt all the days of thy life.
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.
The three yearly feasts kept up communion between God and His people and preserved the face of religion in the nation. One week only was festival, yet their solemn preparation before and serious reflection afterward amounted to observance of the whole month; thus the ceremonies themselves became the means by which God's truth took root in their hearts.
AI summary
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...