Exodus 28:36-39

“Make a plate of pure gold and engrave on it as on a seal: HOLY TO THE LORD. Fasten a blue cord to it to attach it to the turban; it is to be on the front of the turban. It will be on Aaron’s forehead, and he will bear the guilt involved in the sacred gifts the Israelites consecrate, whatever their gifts may be. It will be on Aaron’s forehead continually so that they will be acceptable to the LORD. “Weave the tunic of fine linen and make the turban of fine linen. The sash is to be the work of an embroiderer.