A segment of Matthew Henry's commentary
1. He received the Jews, Rom_15:8. Let not any think hardly or scornfully therefore of those that were originally Jews, and still, through weakness, retain some savour of their old Judaism; for, (1.) Jesus Christ was a minister of the circumcision. That he was a minister, diakonos - a servant, bespeaks his great and exemplary condescension, and puts an honour upon the ministry: but that he was a minister of the circumcision, was himself circumcised and made under the law, and did in his own person preach the gospel to the Jews, who were of the circumcision - this makes the nation of the Jews more considerable than otherwise they appear to be. Christ conversed with the Jews, blessed them, looked upon himself as primarily sent to the lost sheep of the house of Israel, laid hold of the seed of Abraham (Heb_2:16, margin), and by them, as it were, caught at the whole body of mankind. Christ's personal ministry was appropriated to them, though the apostles had their commission enlarged. (2.) He was so for the truth of God. That which he preached to them was the truth; for he came into the world to bear witness to the truth, Joh_18:37. And he is himself the truth, Joh_14:6. Or, for the truth of God, that is, to make good the promises given to the patriarchs concerning the special mercy God had in store for their seed. It was not for the merit of the Jews, but for the truth of God, that they were thus distinguished - that God might approve himself true to this word which he had spoken. - To confirm the promises made unto the fathers. The best confirmation of promises is the performance of them. It was promised that in the seed of Abraham all the nations of the earth should be blessed, that Shiloh should come from between the feet of Judah, that out of Israel should he proceed that should have the dominion, that out of Zion should go forth the law, and many the like. There were many intermediate providences which seemed to weaken those promises, providences which threatened the fatal decay of that people; but when Messiah the Prince appeared in the fulness of time, as a minister of the circumcision, all these promises were confirmed, and the truth of them was made to appear; for in Christ all the promises of God, both those of the Old Testament and those of the New, are Yea, and in him Amen. Understanding by the promises made to the fathers the whole covenant of grace, darkly administered under the Old Testament, and brought to a clearer light now under the gospel, it was Christ's great errand to confirm that covenant, Dan_9:27. He confirmed it by shedding the blood of the covenant.