Exodus 28:40-43

⁴⁰“For Aaron’s sons you shall make tunics, and you shall make sashes for them. And you shall make hats for them, for glory and beauty. ⁴¹So you shall put them on Aaron your brother and on his sons with him. You shall anoint them, consecrate them, and sanctify them, that they may minister to Me as priests. ⁴²And you shall make for them linen trousers to cover their nakedness; they shall reach from the waist to the thighs. ⁴³They shall be on Aaron and on his sons when they come into the tabernacle of meeting, or when they come near the altar to minister in the holy place, that they do not incur iniquity and die. It shall be a statute forever to him and his descendants after him.