Exodus 28:35

His sound shall be heard - The bells were doubtless intended to keep up the people' s attention to the very solemn and important office which the priest was then performing, that they might all have their hearts engaged in the work; and at the same time to keep Aaron himself in remembrance that he ministered before Jehovah, and should not come into his presence without due reverence.

That he die not - This seems an allusion to certain ceremonies which still prevail in the eastern countries. Jehovah appeared among his people in the tabernacle as an emperor in his tent among his troops. At the doors of the tents or palaces of grandees was generally placed some sonorous body, either of metal or wood, which was struck to advertise those within that a person prayed for admittance to the presence of the king, etc. As the tabernacle had no door, but a veil, and consequently nothing to prevent any person from going in, Aaron was commanded to put the bells on his robe, that his sound might be heard when he went into the holy place before the Lord.