Acts 23:20 (KJV)

So he took him, and brought him to the chief captain, and said, Paul the prisoner called me unto him, and prayed me to bring this young man unto thee, who hath something to say unto thee.

Then the chief captain took him by the hand, and went with him aside privately, and asked him, What is that thou hast to tell me?

And he said, The Jews have agreed to desire thee that thou wouldest bring down Paul to morrow into the council, as though they would enquire somewhat of him more perfectly.

But do not thou yield unto them: for there lie in wait for him of them more than forty men, which have bound themselves with an oath, that they will neither eat nor drink till they have killed him: and now are they ready, looking for a promise from thee.

So the chief captain then let the young man depart, and charged him, See thou tell no man that thou hast shewed these things to me.