John 13:14

I have by this my action taught you to love, and to be ready also to serve, one another, and not to think much to serve them even in the lowest and meanest offices by which you can do them good; for we must not think that these words lay a literal obligation upon Christians to wash the feet of others; washing the feet is mentioned but as species pro genere, a single act of service, put for all other acts by which we can be serviceable unto others: so it is also used, 1 Samuel 25:41 1 Timothy 5:10. Some of the ancients seem to have judged this washing of feet to have been instituted as a sacrament, (though in an improper sense), and from hence, though Bellarmine, Maldonate, and others deny it to be a sacrament as well as we, yet probably is the practice in use amongst the papists, to wash certain persons feet every Thursday before Easter; a theatrical ceremony, rather than any thing of solid and profitable use. Our Saviour certainly intends no more by ye ought to wash one another's feet, than, ye ought to serve one another in all offices of love, and not to think yourselves too good, or too great, to do the meanest services to those who are my disciples: and this is that as to which he tells them he had set them an example that they should do as he had done, in other acts of the same kind, though not as to this specific act.