The two questions come from two very different people. Paul asked permission because he wanted to speak, and he soon asked, "suffer me to speak unto the people" (Acts 21:39). Matthew Henry admires the way he asked: "What a humble modest question was this!" Gill says Paul's "modest and respectful way of speaking to the chief captain" shows that "the apostle was one that had had a good education, and was a man of address." The captain's question came from surprise. He had assumed Paul was "that Egyptian" who had led four thousand men into the wilderness (Acts 21:38). Barnes says, "It was natural that the Roman tribune should suppose that Paul was this Egyptian, and that his return had produced this commotion."

The captain answered Paul's request with his own questions: "Canst thou speak Greek?" and "Art not thou that Egyptian...?" (Acts 21:38). Paul answered plainly: "I am a man which am a Jew of Tarsus, a city in Cilicia, a citizen of no mean city: and, I beseech thee, suffer me to speak unto the people" (Acts 21:39). The captain "had given him licence," and Paul stood on the stairs, beckoned with his hand, and when there was "a great silence," he spoke to them "in the Hebrew tongue" (Acts 21:40). Hearing their own language, "they kept the more silence" (Acts 22:2).

The "chief captain" was a chiliarchos, a commander of a thousand soldiers; the ESV calls him a tribune. The "castle" is parembole, a fortress or barracks. Gill (on Acts 21:34) identifies it as the castle of Antonia, formerly called Baris. The soldiers "ran down" from it to the temple crowd, and Paul was carried back up "the stairs" (Acts 21:32, 35).

The captain's question uses Hellenisti, "in Greek." He had taken Paul for an Egyptian rebel (Acts 21:38), so a prisoner speaking Greek surprised him. Paul could speak to the captain in Greek and then turn and speak to the crowd "in the Hebrew tongue" (Acts 21:40).

Agabus's prophecy was coming true: Paul was bound and in the hands of the Gentiles (Acts 21:11, 33). But Paul's chains did not silence him. A short, polite question to a Roman officer turned the stairs of a fortress into a pulpit, and Paul told the crowd how Jesus had met him on the road to Damascus (Acts 22:1-21).

The captain did not know who Paul was. Paul answered by stating who he was, and then used the moment to tell who Jesus is. God was opening a door that would lead to testimony in Jerusalem and then in Rome (Acts 23:11).