Do not labor for the food which perishes, but for the food which endures to eternal life, which the Son of man will give to you; for on him has God the Father set his seal.”
He received circumcision as a sign or seal of the righteousness which he had by faith while he was still uncircumcised. The purpose was to make him the father of all who believe without being circumcised and who thus have righteousness reckoned to them,
But God's firm foundation stands, bearing this seal: “The Lord knows those who are his,” and, “Let every one who names the name of the Lord depart from iniquity.”