Gregory the Great — as excerpted in the Catena Aurea on Luke 7:36-50

“(Hom. 33. in Evan.) For we water the feet of our Lord with tears if we are moved with compassion to any even the lowest members of our Lord. We wipe our Lord’s feet with our hair, when we shew pity to His saints (with whom we suffer in love) by the sacrifice of those things with which we abound.”