Mark 14:43-46

And immediately, while he was still speaking, Judas came, one of the twelve, and with him a crowd with swords and clubs, from the chief priests and the scribes and the elders.

Now the betrayer had given them a sign, saying, "The one I will kiss is the man. Seize him and lead him away under guard."
And when he came, he went up to him at once and said, "Rabbi!" And he kissed him.