What did God make Moses do in the back side of the desert?
God made Moses become a sheepherder for forty years on the back side of the desert, tending sheep in isolation, with almost no human contact. This reduced him to nothing in Egyptian eyes and prepared him for God's service, so at the burning bush he claimed he could not speak.
Les explains that God took Moses out to the back side of the desert and put him in a sheep herd, which in the eyes of an Egyptian was an abomination. Moses had to become a sheepherder for 40 years, living with smelly sheep and almost no contact with humans, until he had become a nothing. Only then did God approach him at the burning bush, where Moses' first excuse was “I can't talk,” because after 40 years of practical silence he had almost forgotten how. That is where God had to take even Moses before He could use him. Les compares this to the Apostle Paul, who was highly educated under Gamaliel, the chief rabbi, and from a wealthy Jewish family, but God had to take him down to a nobody, as I Corinthians 1:27 says God chose the foolish things to confound the wise.