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. Amen, amen, I say to you, no slave is greater than his master nor any messenger greater than the one who sent him. If you understand this, blessed are you if you do it.
(John 13:12-17 NAB)