What did Abraham do to be counted righteous by God?
Abraham did nothing to earn it; he simply believed God, and God saw his faith and imputed righteousness to him. Unlike others whose faith was accompanied by works, Abraham's righteousness was credited by faith alone, before any sacrifice or human effort.
Les explains that Abraham never offered a sacrifice until years later; he did not do anything, he just simply believed God. God saw that man's faith and imputed righteousness. Les contrasts this with Abel, Noah, and other heroes of faith, whose faith was plus works, but Abraham's righteousness came by faith alone, without human doing. So it is with us: without our doing a thing, we simply believe and God counts it.