All that we know about the prophet Agabus comes from two short passages in the Bible. In Acts 11:27–30 Agabus is described as one of several prophets who came from Jerusalem to Syrian Antioch, where Paul was ministering. A prophet was one who received direct messages from God and communicated them to the people. In Acts 11, Agabus predicted (by the Holy Spirit) that a great famine “would spread over the entire Roman world” (verse 28). The text further reports that Agabus was accurate (as we would expect) and that this famine happened during the reign of Emperor Claudius.
As a result of Agabus’s prophecy, the believers in Antioch began to gather money to send to the Christians living in Judea, and they sent the money by the hands of Barnabas and Saul (Paul). This monetary gift was a fitting response because in the ancient Roman Empire there was usually still food available for purchase during a famine, but at dramatically elevated prices. With adequate funds, the Christians in Judea would still have been able to purchase food. Furthermore, the Christians in Judea may well have been cut off from their families and from their normal means of support. The love gift from Antioch was all the more important as a sign of the unity of Jewish (in Judea) and Gentile (in Antioch) believers—a unity for which Paul was continually laboring.
In Acts 21:10–12 we see Agabus once again, this time in Caesarea. Although Luke does not explicitly state that this is the same Agabus as in Acts 11, there is no reason to assume he is a different person. Once again, Agabus is functioning as a prophet, and he comes from Judea (verse 10). He meets Paul as the apostle is on his way to Jerusalem. Agabus takes Paul’s belt and ties up his own hands and feet with it and says, “The Holy Spirit says, ‘In this way the Jewish leaders in Jerusalem will bind the owner of this belt and will hand him over to the Gentiles’” (verse 11). When the people in Paul’s party hear the prophecy of Agabus, they do whatever they can to dissuade Paul from going to Jerusalem, but he is resolute. In this case, it seems the purpose of the prophecy was to mentally prepare Paul for what would befall him rather than to warn him not to go.
In both of these instances, Agabus faithfully delivered the message that God had given him and left it up to the hearers to make an appropriate response. Agabus said no more and no less than what God had told him—and that is the one requirement of a faithful prophet.
After Acts 21, we are told no more about Agabus, but since apostles and prophets are the foundation of the church (Jesus being the cornerstone—Ephesians 2:20), it would be safe to assume that Agabus continued to minister in other situations that are not recorded in Scripture.