Exodus 28:31-35

And thou shalt make the robe of the ephod all of blue. And it shall have a hole for the head in the midst thereof: it shall have a binding of woven work round about the hole of it, as it were the hole of a coat of mail, that it be not rent. And upon the skirts of it thou shalt make pomegranates of blue, and of purple, and of scarlet, round about the skirts thereof; and bells of gold between them round about: a golden bell and a pomegranate, a golden bell and a pomegranate, upon the skirts of the robe round about. And it shall be upon Aaron to minister: and the sound thereof shall be heard when he goeth in unto the holy place before Jehovah, and when he cometh out, that he die not.