{Gave them a sign} (ed(936b)en autois s(886d)eion). Probably just
before he reached the place, though Mark ( Mr 14:44 ) has "had
given" (ded(936b)ei) which certainly means before arrival at
Gethsemane. At any rate Judas had given the leaders to understand
that he would kiss (phil(8873)(935c)) Jesus in order to identify him for
certain. The kiss was a common mode of greeting and Judas chose
that sign and actually "kissed him fervently" (katephil(8873)en,
verse  49 ), though the compound verb sometimes in the papyri has
lost its intensive force. Bruce thinks that Judas was prompted by
the inconsistent motives of smouldering love and cowardice. At
any rate this revolting ostentatious kiss is "the most terrible
instance of the hekousia phil(886d)ata echthrou ( Pr 27:6 )," the
profuse kisses of an enemy (McNeile). This same compound verb
occurs in  Lu 7:38  of the sinful woman, in  Lu 15:20  of the
Father's embrace of the Prodigal Son, and in  Ac 20:37  of the
Ephesian elders and Paul.