John Calvin Commentary Exodus 2:15

"Now when Pharaoh heard this thing, he sought to slay Moses. But Moses fled from the face of Pharaoh, and dwelt in the land of Midian: and he sat down by a well." — Exodus 2:15 (ASV)

Now when Pharaoh heard. Moses acknowledges his fear, though it was not enough to make him withdraw from the work to which he was called. We said before that his zeal was mixed with weakness, but it nevertheless prevailed, so that he performed the duty entrusted to him courageously, yet at the same time timidly.

But this is another proof of his firmness: he is not ashamed of what he had done, so as to try to appease the king, but instead goes into exile. Nor is he so alarmed in this critical time that he sinks down in helplessness or despair; rather, he departs into the land of Midian and prefers wandering in the Desert to a reconciliation with the enemies of the chosen people. But although God appears by this indirect way to turn from His purpose of delivering them, He yet wonderfully carries on His work.

We have already clearly seen that Moses was certainly not yet ready for the difficult struggles that awaited him. Having been brought up delicately and luxuriously in the Court, he was not yet accustomed to the great and continual anxieties over which the rest of the story will show him to be the conqueror. Therefore, God, in a way, withdrew him so that He might gradually make him fit and able to undertake so difficult a task. For the experience of forty years in such a laborious and ascetic way of life greatly helped to prepare him for enduring any hardships, so that the Desert may well be called the school in which he was taught until he was invited to his more difficult charge.

Regarding his sitting down by a well, I interpret it that he sat down there to rest from his fatigue around sunset, so that he might ask for hospitality from the people whom he hoped would come in the evening to draw water. From this unfavorable start, he might have inferred what an uncomfortable reception he was to expect.