Matthew 26:48

Whomsoever I shall kiss. — It is probable, from the known customs (1) of the Jews and (2) of the early Christians (Romans 16:16; 1 Thessalonians 5:26) that this was the usual salutation of the disciples to their Master. St. John, it may be noted, makes no mention of the sign; probably because here, as elsewhere, he seeks to give touches that others had passed over, rather than to repeat what the oral or written teaching of the Church had already made familiar.