After all, it IS the God of the universe you're bargaining with here. Abraham does not seem to be inhibited by his contact with the holy. I'm almost surprised the Lord stoops to answer the question. Let alone God. But the Lord DID reply.
Prayer is as much listening as it is talking.
If Abraham were wise, I keep thinking, he would stop there. He had a two-way conversation with God. He pleaded, God responded. Bingo - answered prayer. Take it at that.