In order to ascertain whether a potential leader of Israel is blessed with the qualities suited for leadership of His people, God assesses them on the basis of their approach to animals.

“The Lord tests the righteous” (Psalms 11:5). On what basis does He test them? It is on the basis of herding sheep. He assessed David on the basis of his treatment of the flock, and found him to be a fine shepherd…he would prevent older sheep from eating before the younger ones; and he would take out the younger ones so they could graze from the soft grass; and then take out the older ones so they could graze from the intermediate quality-grass; and only afterward would he take out the youthful, vigorous sheep so they would eat the rough grass. The Holy One, blessed be He, said: One who knows how to herd the flock in this manner, each animal in accordance with its attributes, is worthy to shepherd My people.

Concerning Moses, too, the Holy One, blessed be He, assessed him only on the basis of his treatment of the flock. Our Sages said: When Moses our teacher, may he rest in peace, was herding Yitro’s flock in the wilderness, a goat fled from him, and Moses chased after it until he came to a shelter. When he arrived at the shelter, he happened upon a pool of water, and the goat stood there to drink. When Moses reached it, he said: I did not know that you were running due to your thirst. You must be tired. He carried the goat on his shoulders and walked back like that. The Holy One, blessed be He, said: You have the mercy to lead a flock belonging to flesh and blood in this manner; I take an oath by your life that you will shepherd My flock, Israel. (Shemot Rabba 2)