36You are to make a plate of pure gold and engrave on it as on a seal: HOLY TO THE LORD.
37Fasten to it a blue cord to mount it on the turban; it shall be on the front of the turban.
38And it will be worn on Aaron’s forehead, so that he may bear the iniquity of the holy things that the sons of Israel consecrate with regard to all their holy gifts. It shall always be on his forehead, so that they may be acceptable before the LORD.
39You are to weave the tunic with fine linen, make the turban of fine linen, and fashion an embroidered sash.
— Exodus 28:36-39