Miriam and Aaron speak against Moses because of the Cushite woman he had married. Their underlying complaint is about authority: they ask whether the Lord has spoken only through Moses and not also through them. The text adds that the Lord heard it, and that Moses was a very humble man, more than anyone else on the face of the earth.
Suddenly the Lord calls the three to the tent of meeting. He comes down in a pillar of cloud, stands at the entrance and calls Aaron and Miriam. He explains that to prophets he speaks in visions and dreams, but with Moses it is different: Moses is faithful in all his house, and with him the Lord speaks face to face, clearly and not in riddles, and he sees the form of the Lord. He asks why they were not afraid to speak against his servant Moses. His anger burns against them, and he departs.
When the cloud withdraws, Miriam is covered with leprosy, white as snow. Aaron admits they have acted foolishly, begs Moses not to hold the sin against them and asks that she not be like a stillborn child. Moses cries out to the Lord: please heal her. The Lord answers that Miriam must stay outside the camp for seven days, as if her father had spat in her face. Miriam is shut outside for seven days, and the people do not move on until she is brought back in. After that they march to the wilderness of Paran.