1 Miriam and Aaron began to talk against Moses because of his Cushite wife, for he had married a Cushite. 2 "Has the LORD spoken only through Moses?" they asked. "Hasn't he also spoken through us?" And the LORD heard this.
9 The anger of the LORD burned against them, and he left them. 10 When the cloud lifted from above the Tent, there stood Miriam—leprous, like snow.
13 So Moses cried out to the LORD, "O God, please heal her!" 14 The LORD replied to Moses, "If her father had spit in her face, would she not have been in disgrace for seven days? Confine her outside the camp for seven days; after that she can be brought back." 15 So Miriam was confined outside the camp for seven days, and the people did not move on till she was brought back.
It seems that Miriam was jealous for recognition. She felt that Moses had done something wrong by marrying a Cushite (possibly Zipporah). Maybe she felt that his wife was beneath his social standing. Maybe it was that she and Aaron were no longer able to influence Moses as they had before his wife was around. There are many theories about why they spoke against him because of his wife.
What we do know is that they were not happy and that Miriam felt somehow slighted. She felt that Moses had done something wrong and wanted to play judge.
God didn't look at it this way. He judged Miriam with leprosy for her comments. Thankfully he was also merciful to her and she was healed after one week.
What can we learn from this story?
1) That we shouldn't look for recognition beyond that which God gives
2) God doesn't look with favor on jealousy
3) God answers prayer and is merciful
4) We shouldn't feel superior as Miriam did because of the supposed sin of others. Let God be the judge
I'm sure there's more to be gleaned from these verses. Is there anything else you see?