Origen

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. Now I tell you before it come, that when it is come, ye may believe that I am He, i. e. of whom that Scripture foretold.