Exodus 28:35-37

35Aaron must wear it when he serves as priest. The sound of the bells must be heard when he comes into and goes out of the Lord’s presence in the holy place so that he won’t die.

36“Make a flower-shaped medallion out of pure gold, and engrave on it (as on a signet ring): Holy to the Lord.

37Fasten a violet cord to it, and tie it so that it’s on the front of the turban.