Mark 14:18

And as they sat Grouping together the four narratives, which, as they approach the Passion, expand into the fulness of a diary, we infer that (i) when the little company had taken their places on the triclinia, the Saviour as Celebrant or Proclaimer of the Feast, remarking that with desire He had desired to eat this Passover before He suffered, took the first cup and divided it amongst them (Luke 22:15-18). (ii) Then followed the unseemly dispute touching priority (Luke 22:24-30), to correct which and to teach them in the most striking manner possible a lesson of humility, He washed His disciples" feet, covered with dust from their walk along the road from Bethany (John 13:1-11). Then the meal was resumed and He reclined once more at the table (John 13:12), the beloved disciple lying on His right, with his head close to the Redeemer's breast.

One of you which eateth with me shall betray me He had already said, after washing their feet, "now ye are clean, but not all" (John 13:10), but at this moment the consciousness of the traitor's presence so wrought upon Him (John 13:21) that He broke forth into words of yet plainer prediction.