Romans 15:8

Now I say.... — Rather, For I say. My doctrine is that Christ came with a two-fold purpose: on the one hand, with a mission to the Jews, the chosen circumcised race, to vindicate to them the truthfulness of God in respect to His promises, by Himself confirming and fulfilling those promises; and, on the other hand, with the object to exhibit the mercy of God in rescuing the Gentiles from their state of condemnation, and giving them cause to glorify God’s name.

Was.... — This is the reading of the Vatican MS. and Paris rescript; the Sinaitic and Alexandrine have, “hath been made.”

For the truth of God — i.e., to make good the truthfulness of God in keeping His promises.