After this Paul stayed many days longer, and then took leave of the brethren and sailed for Syria, and with him Priscilla and Aq'uila. At Cen'chre-ae he cut his hair, for he had taken a vow. And they came to Ephesus, and he left them there; but he himself went into the synagogue and argued with the Jews. When they asked him to stay for a longer period, he declined; but on taking leave of them he said, "I will return to you if God wills," and he set sail from Ephesus. When he had landed at Caesare'a, he went up and greeted the church, and then went down to Antioch. After spending some time there he departed and went from place to place through the region of Galatia and Phryg'ia, strengthening all the disciples..
In a Nutshell
Paul continued his work as he travelled, via Ephesus, back to Antioch.
Questions
Think about this period of Paul's life. Much had been done. Where was home? Did he have plans for retirement?
Luke says "many days." My guess is that this means about 550 days; 18 months. Then, taking leave of them, Paul sailed east. His two tent-making friends were with him to begin with. When Luke tells us that at Cenchreae Paul had a hair-cut because of a vow, he is saying Paul was still a practising Jew. I don't know if his friend Phoebe cut his hair, but, from what Paul writes, she was a great help to the church (Romans 16:1). Paul, with Prisca and Aquila, journeyed on to Ephesus. He stayed there a while, but then the time came for him to move on. Paul told the Ephesian church that he would return to them if he could.
Luke seems to be saying that he knows this part of Paul's life in bare outline only. Earlier Luke had travelled with Paul. Remember that? Later Luke would rejoin Paul's party going up to Jerusalem. Here the account is sketchy. Maybe Luke didn't know exactly why Paul had gone back to Jerusalem and Antioch. When we have difficulties working out what Luke is trying to say here we shouldn't automatically assume it is our problem. Maybe we have scanty information because when it came time to write this up Luke simply didn't know. Maybe he had forgotten to ask Paul about this phase of his ministry. We also get the sense that Luke was emphasising the part played by Priscilla and Aquila. There is also another preacher of the gospel we haven't heard about yet. Paul's tent-making companions were also of great help to him as well.
Maybe Paul was continuing to collect money for the apostolic fund in Jerusalem and why wouldn't he want to report back to Antioch? He and Silas had been commissioned by that church to do the work. They were accountable to the whole church. And wouldn't he want to hear how Barnabas and Mark were getting on?
Landing at Caesarea "Paul went up and greeted the church." What church? Was this the church in Caesarea? I think Luke means Paul went up to Jerusalem. He had a vow. There he greeted the church of the apostles and told them what had been going on. Many Gentiles and Jews were coming to faith. Important progress had been made. Luke does not give us all the details. And we do not know all of what all the Apostles did. The gospel had been taken here, there and everywhere. Paul was still living with a price in his head - maybe his travel up to Jerusalem had to be in great secrecy. We know he went up - but that is about all Luke tells us.
Sometimes very important work goes on nearby and we live for years without knowing about it. We may "keep our ears open" but just because we hear something does not mean it is the most important stuff. God is not limited by our knowledge of His working. He does comes to us in ways that make it easy for us to understand how He works. This is His kindness to us. He understands when things get tough. He knows that it is important for us to find His encouragement. Paul also needed this. I suspect he was tired and needed a rest. He had been busy, used by God for a long period building a strong network of young churches. The work was not finished, but it seems likely he also was happy to go back home for a while and catch up with family and friends at Tarsus.