The Literal Commandment
For seven days you shall present an offering by fire to the LORD. On the eighth day you shall have a holy convocation and present an offering by fire to the LORD; it is an assembly. You shall do no laborious work. (Leviticus 23:36)
The literal commandment is that we should do no laborious work on the eighth day of the Feast of Booths/Tabernacles (Sukkot).