In the seventh aliyah G-d causes a wind to blow, sweeping quail in from the sea. The people gather the quail and start eating the meat. The people who eat the meat gluttonously die of a plague.
Around this time Miriam, Moshe's sister, hears that Moshe had separated from his wife Tzipporah (because of reasons of prophecy), and Miriam speaks against this practice to Aharon because no other prophets did such a thing. G-d considers this loshen hora (evil talk about another) and strikes Miriam with tzora-as. Rashi says that if this is called loshen hora, where Miriam hadn't intended to shame Moshe, how much more so is it when one intends to shame his fellow man.
Moshe then prays that she be cured right away. Nevertheless she is quarantined outside the camp for seven days. When Moshe was put afloat in the Nile as an infant, Miriam waited nearby to see what would happen to him. So, as a reward for what she did as a young girl, midda-keneged-midda (measure for measure) the whole Jewish people wait for her until her cure was complete.
Throughout this whole matter Moshe remains silent and doesn't defend himself, and the Torah calls him the humblest man on earth. Now, how can the man that G-d chose to lead the Jews out of their Egyptian bondage and who received the Torah for them, how can he be the humblest man on earth?
Our Sages explain that Moshe indeed was humble, because he knew that all this wasn't his to be proud of, but that it was G-d Who gave him the opportunity and the ability to do these things. He knew that if G-d had given this opportunity and ability to anybody else that they would have done an even better job.