Matthew 26:25
Judas, who would betray him, answered: is it I, Rabbi? He said to him: you have said so. The specific exchange between Jesus and Judas: Judas' Rabbi (not Lord, as the other disciples used) and Jesus' you have said so is the confirmation that the narrator has already established for the reader — Judas is the betrayer, and Jesus knows it. The Rabbi communicates Judas' understanding of Jesus as a respected teacher rather than the Lord he confessed.