Romans 4:1

What shall we say then that Abraham our father, as pertaining to the flesh, hath found?

The question of what Abraham found as pertaining to the flesh is a question of what a person gains through human effort alone. The answer given in the verses that follow is that Abraham was not justified by works, so he had nothing to boast of before God, though one justified by works would have ground to boast before people. Abraham believed God, and his faith was counted to him as righteousness, credited to him through faith rather than owed to him as a debt for work done. Salvation is therefore by grace, leaving no basis for boasting before God and no ground for claiming a greater reward than others receive. Taken together with Romans 5, the verse also teaches that Christ took humanity upon Himself so that human beings through faith may grasp the divine nature and overcome.