It’s Aaron and Miriam’s turn to do a little complaining as they question if Moses is the only one God speaks through. God explains some things about how he deals with Moses. In his anger Miriam is struck with leprosy for seven days. That pales in comparison to what is coming.

Numbers 12 

Miriam and Aaron spoke against Moses because of the Cushite woman whom he had married: for he had married an Cushite woman.

2 They said “Has the LORD in fact spoken only by Moses? Has he not spoken by us also?” And the LORD heard it.

3 (Now Moses was very meek, above all the men which were on the face of the earth.)

4 The LORD spoke suddenly to Moses, to Aaron and Miriam, “You three come to the tent of meeting.”  And the three of them came.

5 The LORD came down in the pillar of cloud, and stood in the door of the tabernacle, and called Aaron and Miriam: and they both went forward.

6 And he said “Hear now my words: If there is a prophet among you, I the LORD will make myself known to him in a vision, and will speak to him in a dream.

7 My servant Moses is not so, who is faithful in all my house.

8 With him will I speak face to face, directly, and not riddles; and he sees the form of the LORD. Why then are you not afraid to speak against my servant Moses?”

9 The anger of the LORD was kindled against them; and he departed.

10 When the cloud departed from the tabernacle behold, Miriam became leprous, white as snow: and Aaron looked at Miriam and saw that she was diseased.

11 Aaron said to Moses “O my lord, I beg of you, do lay not this sin on us, which we have done foolishly, and have sinned.

12 Do not let her be as one dead, with flesh half consumed when she comes out of his mother’s womb.”

13 And Moses cried to the LORD, saying “Heal her now, O God, I beg of you.” 

14 The LORD said to Moses “If her father had but spit in her face, should she not be ashamed seven days? Let her be shut out from the camp for seven days, and after that let her be received in again.”

15 So Miriam was shut out from the camp seven days: and the people did not move until Miriam was brought in again.

16 Afterwards the people removed from Hazeroth, and pitched in the wilderness of Paran.

See also: Numbers 12 in ESV, HCSB, NASB and NIV via Bible Gateway.