Charles Spurgeon Commentary John 13:11

"For he knew him that should betray him; therefore said he, Ye are not all clean." — John 13:11 (ASV)

For he knew who should betray him; therefore he said, You are not all clean.

They were all washed so far as their feet were concerned, but not all of them had been cleansed in the saved bath which removes the stains of sin.