Exodus 28:42-43

Revised Standard Version

⁴² And you shall make for them linen breeches to cover their naked flesh; from the loins to the thighs they shall reach; ⁴³ and they shall be upon Aaron, and upon his sons, when they go into the tent of meeting, or when they come near the altar to minister in the holy place; lest they bring guilt upon themselves and die. This shall be a perpetual statute for him and for his descendants after him.