John 13:4-7

got up from supper, took off His [outer] robe, and taking a [servant’s] towel, He tied it around His waist. Then He poured water into the basin and began washing the disciples’ feet and wiping them with the towel which was tied around His waist. When He came to Simon Peter, he said to Him, “Lord, are You going to wash my feet?” Jesus replied to him, “You do not realize now what I am doing, but you will [fully] understand it later.”