Charles Ellicott Commentary Exodus 12:16

"And in the first day there shall be to you a holy convocation, and in the seventh day a holy convocation; no manner of work shall be done in them, save that which every man must eat, that only may be done by you." — Exodus 12:16 (ASV)

In the first day there shall be an holy convocation. —The Passover was to be kept on the fourteenth day of Abib, in the evening. The seven following days were to be “days of unleavened bread.” On the first of these, the fifteenth of Abib (Leviticus 23:6), there was to be a “holy convocation,” i.e., a general gathering of the people to the door of the sanctuary for sacrifice, worship, and perhaps instruction. (Compare to Nehemiah 8:1.)

The term “convocation” implies that the people were summoned to attend, and the actual summons appears to have been made by the blowing of the silver trumpets (Numbers 10:2). On the seventh day, the twenty-first of Abib, there was to be another similar meeting. “No manner of work” was to be done on either of these two days, or rather, as explained in Leviticus 23:7-8, “no servile work.”