Exodus 28:35

Aaron must wear it when he ministers. The sound of the bells will be heard when he enters the Holy Place before the LORD and when he comes out, so that he will not die.

(New International Version)

'It shall be on Aaron when he ministers; and its tinkling shall be heard when he enters and leaves the holy place before the LORD, so that he will not die.

(New American Standard Bible)

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.

(King James Version)