Adam Clarke on John 13:18

I speak not of you all - This is a continuation of that discourse which was left off at the tenth verse. The preceding verses may be read in a parenthesis.

I know whom I have chosen - I am not deceived in my choice; I perfectly foresaw every thing that has happened, or can happen. I have chosen Judas, not as a wicked man, nor that he should become such; but I plainly foresaw that he would abuse my bounty, give way to iniquity, deliver me into the hands of my enemies, and bring ruin upon himself.

That the scripture may be fulfilled - Or, thus the scripture is fulfilled. Christ applies to Judas what David had said of his rebellious son Absalom, Psa 41:9, who was one of the most express emblems of this traitor. See on Joh 12:38, Joh 12:39 (note).

He that eateth bread with me - That is, he who was in habits of the utmost intimacy with me.

Hath lifted up his heel - An allusion to a restive, ill-natured horse, that sometimes kicks even the person who feeds and takes care of him.