These instructions close the epistle. From chapter 15:8, it is the exordium, the personal circumstances of the apostle, and salutations.
In verses 8 to 12, he sums up his thoughts respecting God’s dealings with the Jew and the Gentile in the advent of Jesus. He was a minister of the circumcision for the truth of God, to accomplish the promises made to the fathers. For to the Jews God had made promises; but none to the Gentiles. To the latter it was not truth that was in question: but by grace they might through Jesus glorify God for His mercy. For them the apostle quotes passages from Deuteronomy (that is to say, from the Law), from the Psalms, and from the Prophets. ...