{4} And after that many days were fulfilled, the Jews took counsel to kill him:

(4) Paul, who was before a persecutor, now has persecution planned against himself, though it will not happen for a long time.

People's New Testament

9:23 After that many days were fulfilled. A long period, probably at least three years. Luke's narrative is very condensed. He is not writing a history of Saul, but of the founding of the church. We learn from Paul that he spent at this time a long period in Arabia, and after this returned to Damascus (Ga 1:16-18). It was at his return that this persecution broke out.

The Jews took counsel to kill him. For additional information, see 2Co 11:32. At this time Damascus was in the temporary possession of Aretas, an Arabian potentate. Less scrupulous than the Roman rulers, he was willing to please Saul's Jewish enemies, who were numerous and influential, by putting him to death.

Jamieson-Fausset-Brown Bible Commentary

23. And after many days were fulfilled, the Jews took counsel to kill him-Had we no other record than this, we should have supposed that what is here related took place while Saul continued at Damascus after his baptism. But in Ga 1:17, 18 we learn from Paul himself that he "went into Arabia, and returned again unto Damascus," and that from the time of his first visit to the close of his second, both of which appear to have been short, a period of three years elapsed; either three full years, or one full year and part of two others. (See on [1974]Ga 1:16-18). That such a blank should occur in the Acts, and be filled up in Galatians, is not more remarkable than that the flight of the Holy Family into Egypt, their stay there, and their return thence, recorded only by Matthew, should be so entirely passed over by Luke, that if we had only his Gospel, we should have supposed that they returned to Nazareth immediately after the presentation in the temple. (Indeed in one of his narratives, Ac 22:16, 17, Paul himself takes no notice of this period). But wherefore this journey? Perhaps (1) because he felt a period of repose and partial seclusion to be needful to his spirit, after the violence of the change and the excitement of his new occupation. (2) To prevent the rising storm which was gathering against him from coming too soon to a head. (3) To exercise his ministry in the Jewish synagogues, as opportunity afforded. On his return, refreshed and strengthened in spirit, he immediately resumed his ministry, but soon to the imminent hazard of his life.

Matthew Henry's Concise Commentary

9:23-31 When we enter into the way of God, we must look for trials; but the Lord knows how to deliver the godly, and will, with the temptation, also make a way to escape. Though Saul's conversion was and is a proof of the truth of Christianity, yet it could not, of itself, convert one soul at enmity with the truth; for nothing can produce true faith, but that power which new-creates the heart. Believers are apt to be too suspicious of those against whom they have prejudices. The world is full of deceit, and it is necessary to be cautious, but we must exercise charity, 1Co 13:5. The Lord will clear up the characters of true believers; and he will bring them to his people, and often gives them opportunities of bearing testimony to his truth, before those who once witnessed their hatred to it. Christ now appeared to Saul, and ordered him to go quickly out of Jerusalem, for he must be sent to the Gentiles: see ch. 22:21. Christ's witnesses cannot be slain till they have finished their testimony. The persecutions were stayed. The professors of the gospel walked uprightly, and enjoyed much comfort from the Holy Ghost, in the hope and peace of the gospel, and others were won over to them. They lived upon the comfort of the Holy Ghost, not only in the days of trouble and affliction, but in days of rest and prosperity. Those are most likely to walk cheerfully, who walk circumspectly.