Washing the Disciple's Feet is practiced according to the example and commandment Jesus gave. (John 13:14-15)
The practice of believers washing one another's feet is a clear teaching of Jesus. Upon instituting this ordinance with His disciples, He said, "If I then, your Lord and Master, have washed your feet; ye also ought to wash one another's feet. For I have given you an example, that ye should do as I have done to you" (John 13:14,15).
This ordinance, and that of the Lord's Supper, which was established at the same time, are for those who are born-again Christians. As we obey Christ's commandment, we find that the Spirit bears witness of God's approval and brings great joy, as Jesus said in John 13:17.