John 13:3-5, 14-15

that Jesus, knowing that the Father had put everything into His hands, and that He had come from God and was [now] returning to God, 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.

So if I, the Lord and the Teacher, washed your feet, you ought to wash one another’s feet as well. For I gave you [this as] an example, so that you should do [in turn] as I did to you.