On the seventh day shall be a solemn assembly. This is not placed in antithesis to the injunction, six days thou shalt eat unleavened bread, as if the Feast of Unleavened Bread (mazzoth) lasted only for six days and the seventh was to be devoted to a service of a different kind; it simply prescribes that the seventh day of the festival was to be celebrated by an assembling of the whole of those who had come to the feast; the festival was to be wound up with a day of holy convocation, in which no work was to be done (Leviticus 23:36).
On all the days unleavened bread was to be eaten, and on the seventh there was besides to be a solemn assembly to the Lord ( עֲצֶרֶת), called in Le 23:36, "a holy convocation" ( מִקְרָא קֹדֶשׁ).