Exodus 28:35

And it shall be upon Aaron to minister; and his sound shall be heard when he goeth in unto the Holy Place before the Lord, and when he cometh out, that he die not. For as the pomegranates symbolized the sweet odor and the refreshing taste of the Word of God, Proverbs 25:11, so the golden bells symbolized the beautiful sound of the revelation and proclamation of God. The high priest, therefore, as the representative of the congregation and the bearer of the divine testimony, was not to undertake the work of his office without this official vestment, under penalty of death.