This is an oldie but goodie. If you don't know Michael Card's music, you should check it out.
When he had washed their feet and put on his outer garments and resumed his place, he said to them, “Do you understand what I have done to you? You call me Teacher and Lord, and you are right, for so I am. If I then, your Lord and Teacher, have washed your feet, you also ought to wash one another's feet. For I have given you an example, that you also should do just as I have done to you. Truly, truly, I say to you, a servant is not greater than his master, nor is a messenger greater than the one who sent him. If you know these things, blessed are you if you do them. I am not speaking of all of you; I know whom I have chosen. But the Scripture will be fulfilled, ‘He who ate my bread has lifted his heel against me.’ I am telling you this now, before it takes place, that when it does take place you may believe that I am he. Truly, truly, I say to you, whoever receives the one I send receives me, and whoever receives me receives the one who sent me.”
(John 13:1-20 ESV)