Origen
Catena Aurea · Johannesevangelium 13
So after he had washed their feet, and had taken his garments, and was set down again, he said unto them, Know ye what I have done to you? Ye call me Master and Lord: and ye say well; for so I am. If I then, your Lord and Master, have washed your feet; ye also ought to wash one another’s feet. For I have given you an example, that ye should do as I have done to you. Verily, verily, I say unto you, The servant is not greater than his lord: neither he that is sent greater than he that sent him. If ye know these things, happy are ye if ye do them. I speak not of you all: I know whom I have chosen: but that the Scripture may be fulfilled, He that eateth bread with me hath lifted up his heel against me. Now I tell you before it come, that, when it is come to pass, ye may believe that I am he. Verily, verily, I say unto you, He that receiveth whomsoever I send receiveth me; and he that receiveth me receiveth him that sent me. If then I your Lord and Master have washed your feet, ye also ought to wash one another’s feet.
(t. xxxii. 7.) Or thus: This spiritual washing of the feet is done primarily by Jesus Himself, secondarily by His disciples, in that He said to them, Ye ought to wash one another’s feet. Jesus washed the feet of His disciples as their Master, of His servants as their Lord. But the object of the master is to make His disciples as Himself; and our Saviour beyond all other masters and lords, wished His disciples to be as their Master and Lord, not having the spirit of bondage, but the spirit of adoption, whereby they cry, Abba, Father. (Rom. 8:19) So then before they become masters and lords, they need the washing of the feet, being as yet insufficient disciples, and savouring of the spirit of bondage. But when they have attained to the state of master and lord, they then are able to imitate their Master, and to wash the disciples’ feet by their doctrine.