Unleavened bread - See Clarke on Exodus 12:15 (note), and Exodus 12:16 (note).

Seven days thou shalt eat unleavened bread, and in the (d) seventh day [shall be] a feast to the LORD.
(d) Both the seventh and the first day were holy, as in (Exodus 12:16).

Seven days shalt thou eat unleavened bread,.... The Jews (y) gather from this place, and from Deuteronomy 16:8, that the obligation to eat unleavened bread lasted no longer than the first night of the seven days, but on the rest it was enough if they abstained from leavened bread, and it was lawful for them to eat of other food as they pleased; see Gill on Exodus 12:15, but the words are very express in both places, and so in the following verse, for eating unleavened bread, as well as abstaining from leavened; and, indeed, otherwise it would not be so clear and plain a commemoration of their case and circumstances, in which they were when they came out of Egypt; this bread of affliction, as it is called, Deuteronomy 16:3 being what would put them in mind thereof:
and in the seventh day shall be a feast to the Lord; an holy convocation, in which no work was to be done, except what was necessary for preparing food to eat, see Exodus 12:16.
(y) In Siphre apud Manasseh Ben lsrael. Conciliat. in loc.