Exodus 28:36

28:36 “You are to make a plate of pure gold and engrave on it the way a seal is engraved: “Holiness to the Lord.”

Exodus 28:38

28:38 It will be on Aaron’s forehead, and Aaron will bear the iniquity of the holy things, which the Israelites are to sanctify by all their holy gifts; it will always be on his forehead, for their acceptance before the Lord.