Origen
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. Jesus answered and said unto him, What I do thou knowest not now; but thou shalt know hereafter.
(t. xxxii.) Or our Lord insinuates that this is a mystery. By washing and wiping, He made beautiful the feet of those who were to preach glad tidings, (Is. 52:7.) and to walk on that way of which He tells them, I am the way. (infr. 14:6) Jesus laid aside His garments that He might make their clean feet still cleaner, or that He might receive the uncleanness of their feet unto His own body, by the towel with which alone He was girded: for He hath borne our griefs. Observe too, He chose for washing His disciples’ feet the very time that the devil had put it into the heart of Judas to betray Him, and the dispensation for mankind was about to take place. Before this the time was not come for washing their feet. And who would have washed their feet in the interval between this and the Passion? During the Passion, there was no other Jesus to do it. And after it the Holy Ghost came upon them, by which time they should already have hadtheir feet washed. This mystery, our Lord says to Peter, is too great for thee to understand now, but thou shalt know it hereafter when thou art enlightened.