John 6:71

Verse 71. He spake of Judas, &c. There is no evidence that Jesus designated Judas so that the disciples then understood that it was he. It does not appear that the apostles even suspected Judas, as they continued to treat him afterward with the same confidence, for he carried the bag, or the purse containing their little property (Joh 12:6; 13:29); and at the table, when Jesus said that one of them would betray him, the rest did not suspect Judas until Jesus pointed him out particularly, Joh 13:26. Jesus spoke of one, to put them on their guard, to check their confidence, and to lead them to self-examination.