What does Acts 4:3 mean?

The priests, their temple guard, and other Jewish leaders of the Sadducee sect have arrested Peter and John for teaching that Jesus rose from the dead (Acts 4:1–2). Peter and John entered the temple for the afternoon prayers. After prayers, they spoke to a crowd of people about Jesus (Acts 3). Now, it's too late to get the Sanhedrin together to investigate them, so the guards put them in prison for the night.

Jesus told His disciples they would experience this kind of harassment. He said, "They will lay their hands on you and persecute you, delivering you up to the synagogues and prisons, and you will be brought before kings and governors for my name's sake" (Luke 21:12). This is not the last time either Peter or John will face prison. The Sanhedrin will arrest, question, and beat all the apostles (Acts 5:17–42). Then, Herod Agrippa I will kill James and imprison Peter. An angel will rescue Peter, and he will escape Jerusalem (Acts 12:1–19).

The apostles will experience much worse: tradition says all but John will die for their faith. But the persecution starts slowly. God will often increase our trials slowly to develop and prove our faithfulness to Him. Not that He needs to know how faithful we are, but we need to know. The Sanhedrin will release Peter and John. The two will go back to the group of believers, and they will all pray—not for protection, but that they would continue to teach in boldness (Acts 4:23–31). Later, after the Sanhedrin beats the apostles and releases them, the apostles leave "rejoicing that they were counted worthy to suffer dishonor for the name" (Acts 5:41).

And their trials will not go unrewarded. "The word of God continued to increase, and the number of the disciples multiplied greatly in Jerusalem, and a great many of the priests became obedient to the faith" (Acts 6:7). Their prosecutors come to accept that Jesus rose from the dead, repent of their sins, and follow Him.