Their lying in wait (tēn enedran). Old word from en (in) and hedra (seat), ambush. In N.T. only here and Act 25:3. Accusative object of akousas.
He came (paragenomenos). Second aorist middle participle of paraginomai. It may mean, “having come upon them” and so discount their plot, a graphic touch. Vincent thinks that some Pharisee, since Paul was a Pharisee and so a member of the “guild,” told his nephew of the plot. Perhaps, and perhaps not.
Told Paul (apēggeilen tōi Paulōi). This nephew is not known otherwise. He may be a student here from Tarsus as Paul once was. Anyhow he knows what to do when he catches on to the conspirators. He had enough address to get into the barracks where Paul was. He ran the risk of death if discovered.