Exodus 12:23

12:23 For the Lord will pass through to strike Egypt, and when he sees the blood on the top of the doorframe and the two side posts, then the Lord will pass over the door, and he will not permit the destroyer to enter your houses to strike you.

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.