John 13:12-15

So when he had washed their feet, and taken his garments, and sat 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, the Lord and the Master, have washed your feet, ye also ought to wash one another's feet. For I have given you an example, that ye also should do as I have done to you.