"I will make my opinions widely known" (Job 36:3). God called Abraham from the east — "calling a bird of prey from the east, a man of my counsel from a distant land" (Isaiah 46:11). Abraham was the one who would inform God about His world, the midrash says, in the same way a worker in the field informs the master about what is growing. The labor of the trials is the labor of someone who cares deeply about the outcome.
God is known in Judah (Psalm 76:2) — and the knowledge spreads from Judah outward because of Abraham. Before Abraham, the nations knew God only as a cosmic abstraction, if at all. After Abraham walked from Ur to Canaan, argued with kings, welcomed strangers, and interceded for Sodom, the name of God became attached to a specific covenant with a specific people. The nations could point to something. The abstraction had a history.
The midrash uses the image of the craftsman: a skilled worker does not need to be told what the master wants — he knows the master's taste and works accordingly. Abraham had internalized the divine will so completely that he needed no explicit instruction for most of the covenant's demands. He had extrapolated them from his relationship with God. This is why the verse says he kept God's voice, charge, commandments, statutes, and laws (Genesis 26:5) — he heard the harmony beneath the individual notes and played the whole score.