I shall return (anakampsō). Future active indicative of anakamptō, old verb to bend back, turn back (Mat 2:2).
If God will (tou theou thelontos). Genitive absolute of present active participle. This expression (ean with subjunctive) occurs also in 1Co 4:19; 1Co 16:7; Jam 4:15. Such phrases were common among Jews, Greeks, and Romans, and are today. It is simply a recognition that we are in God’s hands. The Textus Receptus has here a sentence not in the best MSS.: “I must by all means keep this feast that cometh in Jerusalem.” This addition by D and other documents may have been due to a desire to give a reason for the language in Act 18:22about “going up” to Jerusalem. Whether Paul said it or not, it was in the spring when he made this journey with a company of pilgrims probably going to the feast of Pentecost in Jerusalem. We know that later Paul did try to reach Jerusalem for Pentecost (Act 20:16) and succeeded. As the ship was leaving, Paul had to go, but with the hope of returning soon to Ephesus as he did.