Romans 1:5

δἰ οὗ ἐλάβομεν χάριν καὶ ἀποστολὴν εἰς ὑπακοὴν πίστεως ἐν πᾶσιν τοῖς ἔθνεσιν ὑπὲρ τοῦ ὀνόματος αὐτοῦ

Through whom we received grace and apostleship to bring about obedience of faith in all the nations for his name


 * ἐλάβομεν - Aorist active indicative 1P pl. The ομεν ending is nice and clear.
 * Notice Paul is speaking with a kind of "royal we". Apparently common in that era.
 * χάριν καὶ ἀποστολὴν - some discussion on the internet that this could be a form of "hendiadys", that is, one single thing said in two ways like "grace and favour" or "nice and warm". In this interpretation, the grace=apostleship. Elsewhere Paul does say that his apostleship is a matter of special grace given to him. Or we can just call it as we see it, and infer that Paul has received two things, grace and then a mission to go and evangelize.
 * εἰς - in, into. Where's the verb? Have to go all the way back to ἐλάβομεν? In this case then, all the stuff after ἀποστολὴν is not a another clause, but the elaboration (the full "title") of what Paul's apostleship. E.g. Like Secretary for Defence, Minister for Tourism. So Paul is Apostle for obedience of faith among gentiles.
 * ὑπακοὴν πίστεως - NET bible footnote gives a few options being debated about what type of genitive πίστεως this is. Mounce also has a blog article on this. It could be 1) objective genitive: obedience with faith as object, hence obedience to the faith 2) subjective genitive: faith is the subject. Obedience resulting from/produced by faith 3) attributive - a believing kind of obedience 4) genitive of apposition (Mounce I think calls this epexegetical genitive) where the genitive word gives more information about the head word. Thus, obedience (namely, that is) faith.
 * Mounce's point is that sometimes grammar doesn't give the answer.
 * The NET bible notes also suggests that Paul might be deliberately ambiguous. That's plausible because we also do this in prose and poetry, where we intend that the reader take this at several levels. Paul might be saying, take it various ways. All are right. Obedience and faith are so closely linked they might as well be the same thing. One implies the other. You can't have one without the other. Faith inevitably produces obedience, obedience produces greater faith. So perhaps it doesn't matter.