Ye are clean, refers to the eleven; but not all, to Judas. He was unclean, first, because he cared not for the poor, but was a thief; secondly, because the devil had put it into his heart to betray Christ. Christ washes their feet after they are clean, shewing that grace goes beyond necessity, according to the text, He that is holy, let him be holy still. (Apoc. 22:11)
Reproduced in full. Translation: Oxford 1841 (Newman), public domain (Public domain).
Also cites: t. xxxii. 6.