A.T. Robertson Commentary Mark 14:18

"And as they sat and were eating, Jesus said, Verily I say unto you, One of you shall betray me, [even] he that eateth with me." — Mark 14:18 (ASV)

As they sat (ανακειμενων αυτων). Reclined, of course. It is a pity that these verbs are not translated properly in English. Even Leonardo da Vinci in his immortal painting of the Last Supper has Jesus and his apostles sitting, not reclining. Probably he took an artist's license for effect.

Even he that eateth with me (ο εσθιων μετ' εμου). See Ps 4:9. To this day the Arabs will not violate hospitality by mistreating one who breaks bread with them in the tent.