Exodus 28:39-43

Weave the tunic with finely-spun linen and make the turban of the same material, and also make a sash and have it embroidered. Make tunics, sashes, and headdresses for Aaron's sons, so that they will look splendid and dignified. Put these clothes on your brother Aaron and his sons and then anoint them and ordain them. Dedicate them so that they can serve me as priests. Make linen undershorts to cover their bare bodies, reaching from waist to thigh. Aaron and his sons are to wear them when they enter the Tent of Meeting or when they approach the altar to serve in the Holy Place, so that they will not bring guilt on themselves and die. This is a law for Aaron and his descendants forever.