Yochanan (Jhn) 13:12-15

After he had washed their feet, taken back his clothes and returned to the table, he said to them, “Do you understand what I have done to you? You call me ‘Rabbi’ and ‘Lord,’ and you are right, because I am. Now if I, the Lord and Rabbi, have washed your feet, you also should wash each other’s feet. For I have set you an example, so that you may do as I have done to you.