Exodus 28:39-40, 43

“You shall weave the tunic of checkered work of fine linen, and shall make a turban of fine linen, and you shall make a sash, the work of a weaver. “For Aaron’s sons you shall make tunics; you shall also make sashes for them, and you shall make caps for them, for glory and for beauty.

They shall be on Aaron and on his sons when they enter the tent of meeting, or when they approach the altar to minister in the holy place, so that they do not incur guilt and die. It shall be a statute forever to him and to his descendants after him.