Adam Clarke on Numbers 12:2

Hath the Lord indeed spoken only by Moses? - It is certain that both Aaron and Miriam had received a portion of the prophetic spirit, (see Exo 4:15, and Exo 15:20), and therefore they thought they might have a share in the government; for though there was no kind of gain attached to this government, and no honor but such as came from God, yet the love of power is natural to the human mind; and in many instances men will sacrifice even honor, pleasure, and profit to the lust of power.