Jn 13:12-15
So when he had washed their feet (and) put his garments back on and reclined at table again, he said to them, "Do you realize what I have done for you? You call me 'teacher' and 'master,' and rightly so, for indeed I am. If I, therefore, the master and teacher, have washed your feet, you ought to wash one another's feet. I have given you a model to follow, so that as I have done for you, you should also do.
