6 just as Abraham ‘believed God and it was credited to him as righteousness.’This is a quote from Genesis 15:6, but is not presented as such.
7 Now you must know that only those who are of faith are ‘sons’ of Abraham. 8 Further, the Scripture, foreseeing that God would justify the nations by faith,The form of the verb is ambiguous as to mood; it could be either Indicative or Subjunctive. The Indicative would give a direct quote, "God justifies the nations by faith", but we don’t find this quote in the OT, so I chose the Subjunctive. Notice that ‘the Scripture’ is personified! It/He sees/knows in advance what God is going to do. proclaimed the Gospel in advance to Abraham: "All the nations will be blessed through you."This is a direct quote from Genesis 12:3, which, of course, had not been written yet in Abraham’s day (in his day the only written Scripture available was the book of Job). Notice that the personification of ‘Scripture’ continues; It/He is the One who said this to Abraham, so all we need to do is go back to Genesis to find out who it is—Jehovah Himself, presumably the Son! 9 So then, those who are of faith are blessed along with Abraham, the faithful.