Exodus 35:2
For six days work may be done, but the seventh day shall be your holy day, a Sabbath of complete rest to the LORD. Whoever does any work on that day must be put to death.
What it says
Work belongs to six days, but the seventh is a holy Sabbath of complete rest to the LORD, and violation carries the death penalty.
What it is doing
It states the central command and gives it grave force.
In context
1Then Moses assembled the whole congregation of Israel and said to them, “These are the things that the LORD has commanded you to do: 2For six days work may be done, but the seventh day shall be your holy day, a Sabbath of complete rest to the LORD. Whoever does any work on that day must be put to death. 3Do not light a fire in any of your dwellings on the Sabbath day.”