Paul’s nephew warned that some Jews had plotted to kill Paul.

Acts 23:16-22

16 But the son of Paul’s sister heard what they were planning to do, so he went into the barracks and told Paul. 17 When Paul heard that, he called one of the officers and said to him, “Please take this young man to the commander, because he needs to tell him something important.” 18 So the officer took Paul’s nephew to the commander. The officer said to the commander, “That prisoner, Paul, called me and said, ‘Please take this young man to the commander, because he needs to tell him something important.’ ” 19 The commander took the young man by the hand, led him off by himself, and asked him, “What do you (sg) need to tell me?” 20 The young man said, “There are some [SYN] Jews who have planned to ask you (sg) to bring Paul before their Council tomorrow. They will say that they want to ask him some more questions. But that is not true. 21 Do not do what they ask you (sg) to do, because there are more than 40 Jewish men who will be hiding and waiting to attack Paul when he passes by on the way to the Council. They even promised/vowed to God that they will not eat or drink anything until they have killed Paul. They are ready to do it, and right now they are waiting for you (sg) to agree to do what they are asking you to do.” 22 The commander said to Paul’s young nephew, “Do not tell anyone that you (sg) have told me about their plan.” Then he sent the young man away.