Do not work for the food that perishes, but for the food that endures to eternal life, which the Son of Man will give to you. For on him God the Father has set his seal.”
He received the sign of circumcision as a seal of the righteousness that he had by faith while he was still uncircumcised. The purpose was to make him the father of all who believe without being circumcised, so that righteousness would be counted to them as well,
But God’s firm foundation stands, bearing this seal: “The Lord knows those who are his,” and, “Let everyone who names the name of the Lord depart from iniquity.”