Probably those bells were intended to inform the people by their sound, that the high priest when rising up by which they rung was then going to offer incense; so that they which were in the outward court might join in prayer. See Luke 1:9-10. Some have thought, that that expression in the Psalms hath an allusion to it: Psalms 89:15. But whether this or not, it is sweet to hear the bells of Christ's gospel, I mean the joyful sound of his words: and in the same moment to recollect, that he as our high priest is gone in before the throne, there to appear in the presence of God for us. Hebrews 9:23-24.
Related Commentaries of Exodus 28:33
Exodus 28:33-35
33 And beneath upon the hemc of it thou shalt make pomegranates of blue, and of purple, and of scarlet, round about the hem thereof; and bells of gold between them round about:
34 A golden bell and a pomegranate, a golden bell and a pomegranate, upon the hem of the robe round about.
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.