Exodus 28:33-35

You shall make pomegranates of blue, purple, and scarlet fabric all around its hem, with gold bells between them; a golden bell and a pomegranate, a golden bell and a pomegranate, all around the [bottom] hem of the robe. Aaron shall wear the robe when he ministers, and its sound shall be heard when he goes [alone] into the Holy Place before the LORD, and when he comes out, so that he will not die there.