Exodus 28:36-38

“Next make a medallion of pure gold, and engrave it like a seal with these words: HOLY TO THE LORD. Attach the medallion with a blue cord to the front of Aaron’s turban, where it must remain. Aaron must wear it on his forehead so he may take on himself any guilt of the people of Israel when they consecrate their sacred offerings. He must always wear it on his forehead so the LORD will accept the people.