Where did Moses and Paul receive their respective revelations from God?
Moses received the law from God at Mount Sinai, and Paul received the doctrines of grace from God, also at Mount Sinai, according to the context. These two men are presented as the greatest in human history, each given revelation in his respective area.
Les explains that Moses was the giver of the law to the nation of Israel at Mount Sinai. Then he brings in the Apostle Paul, saying he thinks Paul was also at Mount Sinai, where God gave him the doctrines of grace. Les holds these two men up as the greatest two in all of human history, each in his own respective area, and notes that both made a statement concerning the nation of Israel. This comparison supports his larger point that God is not through with Israel. Although most of Christendom, including Roman Catholics and Protestants, thinks God is all through with the nation because they rejected and crucified their Messiah, Les insists that little Israel is still God's covenant people, even though He has set them aside.