Augustine of Hippo
Catena Aurea · Johannesevangelium 13
Then cometh he to Simon Peter: and Peter said unto him, Lord, dost thou wash my feet? Jesus answered and said unto him, What I do thou knowest not now; but thou shalt know hereafter. Peter saith unto him, Thou shalt never wash my feet. Jesus answered him, If I wash thee not, thou hast no part with me. Simon Peter saith unto him, Lord, not my feet only, but also my hands and my head. Jesus saith to him, He that is washed needeth not save to wash his feet, but is clean every whit: and ye are clean, but not all. For he knew who should betray him; therefore said he, Ye are not all clean.
Or thus: We must not suppose that Peter was afraid and refused, when the others had willingly and gladly submitted to the washing. Our Lord did not go through the others first, and to the first of the Apostles afterwards; (for who is ignorant that the most blessed Peter was the first of all the Apostles?) but began with him: and Peter being the first to whom He came, was afraid; as indeed any of the others would have been.