Acts 5:25

‘And there came one and told them, “Behold, the men whom you put in the prison are in the temple standing and teaching the people.” '

To their chagrin someone arrived hotfoot to report that news had come from the Temple that the prisoners were again free and preaching in the Temple courtyards. The chief priests would be perplexed and furious at the same time. Perplexed because they did not know how they had got there but furious because they might at least have had the decency to go into hiding. This rightly saw this as a flagrant and deliberate challenge to their authority. They did not stop to pause and consider that as it was God's Temple, and that He had the right to give them permission to preach there. (Luke has stressed that it was God Who had told the Apostles to go back there to proclaim the word of life). They simply became more and more angry.