For if Abraham was justified or declared righteous by God on the basis of his works and accomplishments, he would have grounds for boasting and taking credit—but he has no such grounds for boasting before God.
If, in fact, Abraham was justified by works, he had something to boast about—but not before God.
NMVFor if Avraham [Exalted Father] were justified by works, he has [whereof] to glory; but not before God-The Father.
OJBFor if Avraham Avinu was accounted to be YITZDAK IM HASHEM and acquitted before Hashem on the basis of ma'asim (of gezetz), he has something to boast about. But not before Hashem!
TCENTIf Abraham was justified by works, he has something to boast about, but not before God.
T4TIf it was because of Abraham’s doing good things that the record of his sins was erased {that God erased the record of his sins}, Abraham could then have been able to boast about that to people, but he would not have had any basis to boast to God about it.