It was reckoned unto him for righteousness (elogisqh ei dikaiosunhn). First aorist passive indicative of logizomai. See on "1Co 13:5" for this old word. He quotes Genesis 15:6 and uses it at length in Romans 4:3 to prove that the faith of Abraham was reckoned "for" (ei, good Koin idiom though more common in LXX because of the Hebrew) righteousness before he was circumcised. James ( James 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.