Exodus 28:35-37

35The robe will be worn by Aaron whenever he ministers, and its sound will be heard when he enters the sanctuary before the Lord and when he exits, so that he does not die.

36“You are to make a pure gold medallion and engrave it, like the engraving of a seal: Holy to the Lord.

37Fasten it to a cord of blue yarn so it can be placed on the turban; the medallion is to be on the front of the turban.