Exodus 30:21
they shall wash their hands and their feet, that they not die. And he and his seed shall have it as a perpetual statute throughout their generations.
Exodus 28:43
And they shall be upon Aaron and upon his sons when they enter into the tabernacle of the testimony or when they come near unto the altar to serve in the sanctuary that they not bear iniquity and die: This shall be a perpetual statute unto him and his seed after him.
Exodus 27:21
In the tabernacle of the testimony outside the veil, which shall be before the ark of the testimony, Aaron and his sons shall order them from evening to morning before the LORD; it shall be a perpetual statute of the sons of Israel for their generations.