Exodus 30:21
They must wash their hands and feet, so that they will not die. This is a long lasting rule that they and their descendants are to observe.
Exodus 28:43
Aaron and his sons must wear them when they go into the tent of meeting or when they come near the altar to serve as priests in the holy place. They will be blameless and will not die. This is a long lasting law for him and his descendants.
Exodus 27:21
Keep the lamps lit in the tent of meeting outside the canopy where the words of my covenant are. Aaron and his descendants must keep the lamps lit in Jehovah's presence from evening until morning. This is a long lasting law among the Israelites for generations to come.