Exodus 28:36–37
36 “You shall make ra plate of pure gold and engrave on it, like the engraving of a signet, s‘Holy to the Lord.’ 37 And you shall fasten it on the turban by a cord of blue. It shall be on the front of the turban.
Exodus 29:6
6 gAnd you shall set the turban on his head and put the holy crown on the turban.