G‑d appointed 70 elders to assist Moses. Moses’ wife remarked to his sister Miriam that these elders would probably separate from their wives, just as Moses had separated from her in order to be ready for prophecy at any moment. Hearing this, Miriam, together with Aaron, disapproved of Moses’ behavior. G‑d told Miriam and Aaron that Moses had acted correctly, since he had to be ready at all times for Divine communication, which was not the case with other prophets. G‑d afflicted Miriam with the skin disease of tzara’at, which specifically results from slander. Moses then prayed for Miriam’s recovery, and G‑d healed her.
True Humility
וְהָאִישׁ מֹשֶׁה עָנָו מְאֹד מִכֹּל הָאָדָם אֲשֶׁר עַל פְּנֵי הָאֲדָמָה: (במדבר יב:ג)
Moses was exceedingly humble, more so than any other person on earth. Numbers 12:3

Humility is not the result of underestimating one’s true worth. Moses understood very well that he was an extraordinary individual, who had been chosen by G‑d to lead the Jewish people out of Egypt and to receive the Torah on their behalf. However, Moses also thought that had G‑d given his lofty traits to someone else, that person would have been able to reach an even higher level than he had attained.

Humility is often misunderstood as simply the lack of boastfulness: We are “humble” if we feel superior to others so long as we don’t boast about it! True humility, however, is learned from Moses. We should be fully aware of whatever greatness we possess, but attribute it to G‑d rather than to ourselves. This allows us to respect other people and see them in a positive light, inasmuch as G‑d has blessed them with their own unique qualities.1