Now in these days prophets came down from Jerusalem to Antioch. And one of them named Agabus stood up and foretold by the Spirit that there would be a great famine over all the world (this took place in the days of Claudius). So the disciples determined, every one according to his ability, to send relief to the brothers living in Judea. 30 And they did so, sending it to the elders by the hand of Barnabas and Saul. (Acts 11:27-30)
Because of the prophecy it was possible for the believers in Antioch to save up money in advance for the relief of the coming famine in Judea.
God commands us to love one another. This prophecy shows us one way in which God will help believers who want to serve each other.