Deuteronomy 16:8
Six days thou shalt eat unleavened bread: and on the seventh day shall be a solemn assembly to the LORD thy God: thou shalt do no work therein. Six days thou shalt eat unleavened bread: and on the seventh day shall be a solemn assembly to the LORD thy God: thou shalt do no work therein.
After six days of eating unleavened bread, the seventh day is a solemn assembly to the Lord. No work is to be done on that day. It stands among the appointed religious seasons when unnecessary work was set aside so that full attention could be devoted to remembering God's blessings.