Adam Clarke on Numbers 12:10

Miriam became leprous - It is likely Miriam was chief in this mutiny; and it is probable that it was on this ground she is mentioned first, (see Num 12:1), and punished here, while Aaron is spared. Had he been smitten with the leprosy, his sacred character must have greatly suffered, and perhaps the priesthood itself have fallen into contempt. How many priests and preachers who deserved to be exposed to reproach and infamy, have been spared for the sake of the holy character they bore, that the ministry might not be blamed! But the just God will visit their transgressions in some other way, if they do not deeply deplore them and find mercy through Christ. Nothing tends to discredit the work of God so much as the transgressions and miscarriages of those who minister in holy things.