{It was reckoned unto him for righteousness} (elogisth(8820)eis
dikaiosun(886e)). First aorist passive indicative of logizomai.
See on 气Co 13:5| for this old word. He quotes  Ge 15:6  and uses
it at length in  Ro 4:3ff.  to prove that the faith of Abraham
was reckoned "for" (eis, good _Koin(825f) idiom though more common
in LXX because of the Hebrew) righteousness before he was
circumcised. James ( Jas 2:23 ) quotes the same passage as proof
of Abraham's obedience to God in offering up Isaac (beginning to
offer him). Paul and James are discussing different episodes in
the life of Abraham. Both are correct.