When it was day, the Jews made a plot and bound themselves by an oath neither to eat nor drink till they had killed Paul. There were more than forty who made this conspiracy. They went to the chief priests and elders and said, “We have strictly bound ourselves by an oath to taste no food till we have killed Paul. Now therefore you, along with the council, give notice to the tribune to bring him down to you, as though you were going to determine his case more exactly. And we are ready to kill him before he comes near.”

Now the son of Paul's sister heard of their ambush, so he went and entered the barracks and told Paul. Paul called one of the centurions and said, “Take this young man to the tribune, for he has something to tell him.” So he took him and brought him to the tribune and said, “Paul the prisoner called me and asked me to bring this young man to you, as he has something to say to you.” The tribune took him by the hand, and going aside asked him privately, “What is it that you have to tell me?” And he said, “The Jews have agreed to ask you to bring Paul down to the council tomorrow, as though they were going to inquire somewhat more closely about him. But do not be persuaded by them, for more than forty of their men are lying in ambush for him, who have bound themselves by an oath neither to eat nor drink till they have killed him. And now they are ready, waiting for your consent.” So the tribune dismissed the young man, charging him, “Tell no one that you have informed me of these things.”

Then he called two of the centurions and said, “Get ready two hundred soldiers, with seventy horsemen and two hundred spearmen to go as far as Caesarea at the third hour of the night. Also provide mounts for Paul to ride and bring him safely to Felix the governor.” (ESV)