“And it came about, that, when I had returned to Jerusalem, and while I prayed in the temple, I fell into a trance, and saw him saying to me, ‘Make haste, and get you quickly out of Jerusalem, because they will not receive of your testimony concerning me.' ”
He then omits all mention of his activities in Damascus and Arabia, and hurries on to the fact that he returned to Jerusalem, to praying in the Temple. He wants them to see that he was a faithful Jerusalemite even then. His experience did not mean that he had ceased to be a Jew, or that he had forsaken the old places and ideas. No, the fact was that it had made him a better Jew. And he had wanted to serve God in Jerusalem. But he was too honest to stop there. Had he done so things might have quietened down a little. But he knew that it would not be long before the question of his activities among the Gentiles again cropped up, so he wanted the true situation to be known. And he also wanted to challenge this crowd about their own view of Jesus. Humanly speaking it may have been a mistake (it depends on what you think he should have been after). But Paul was not in human hands.
So he went on to describe how while he was in the Temple he had fallen into a trance. Like Isaiah of old he had seen the Lord (Isaiah 6). And there he had heard the voice of the Lord. It was the Lord Himself Who had warned him to leave Jerusalem in haste because Jerusalem would not receive his testimony. Just as God had warned Isaiah of old that the people would not hear, so God had warned him that hearing they would not understand, and seeing they would not perceive. But whereas Isaiah had been told to go on preaching to the Jews, and only later learned that the message was also to go out to the Gentiles, it was to be different with Paul. He was to fulfil what Isaiah had looked forward to. He had come to the Jew first, and the Jews had not heard him. So now he was to go to the Gentiles.
As we know at the time when he was preaching in Jerusalem certain Hellenistic Jews were at that time plotting to kill him as they had Stephen (Acts 9:29). But he does not mention that. He simply wants them to see that he did not desert Jerusalem in line with his own purposes, or without trying to serve the Jews. He did it because he received a message from the God of Israel in the Temple of the God of Israel as to what he should do. Like Isaiah of old he did what he was told.
We may note that Peter also went to the Gentiles as a result of a trance in which God spoke to him (Acts 10:10; Acts 11:5). In both cases they responded to the direct command of God.