Exodus 16:23

16:23 He said to them, “This is what the Lord has said: ‘Tomorrow is a time of cessation from work, a holy Sabbath to the Lord. Whatever you want to bake, bake today; whatever you want to boil, boil today; whatever is left put aside for yourselves to be kept until morning.’”

Exodus 28:43

28:43 These must be on Aaron and his sons when they enter to the tent of meeting, or when they approach the altar to minister in the Holy Place, so that they bear no iniquity and die. It is to be a perpetual ordinance for him and for his descendants after him.