Exodus 31:14-15

14“ ‘Observe the day of rest because it is holy to you. Whoever treats it like any other day must be put to death. Whoever works on that day must be excluded from the people.

15You may work for six days, but the seventh day is a day of rest—a holy day, a day when you don’t work. It is holy to the Lord. Whoever works on that day must be put to death.