Exodus 28:35

Exo 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.

Ver. 35. And his sound shall be heard. ] Necesse erat ut Pontifex totus vocalis ingrederetur sanctuarium, ne forte non audito sonitu, morte lueret silentium. A "dumb dog" is a child of death. Isa 56:10 Ministers must be both able and "apt to teach" upon all occasions.