Ralph Erskine (The Pollution and Defilement of Sin), Sermons 1:269:
There is also a progressive daily washing from the daily pollutions that are contracted; and this washing the godly themselves daily need. Though they need not to be regenerated again, or a new regeneration of their nature, yet they need always a new conversion and washing of their heart and way; hence Christ saith to Peter, John 13:10, “He that is washed, needeth not save to wash his feet.” Sins contracted, by daily unwatchfulness, put the people of God under a necessity of daily washing, though not a washing of the whole person; for that is done in regeneration, wherein the state is changed. “He that is washed, needeth not save to wash his feet.” The feet of his affections, the feet of his conversation, the steps of his daily walk. But there are multitudes that were never washed at all; they must wash head, and heart, and all; their nature and state need washing as well as their heart and life.
There is also a progressive daily washing from the daily pollutions that are contracted; and this washing the godly themselves daily need. Though they need not to be regenerated again, or a new regeneration of their nature, yet they need always a new conversion and washing of their heart and way; hence Christ saith to Peter, John 13:10, “He that is washed, needeth not save to wash his feet.” Sins contracted, by daily unwatchfulness, put the people of God under a necessity of daily washing, though not a washing of the whole person; for that is done in regeneration, wherein the state is changed. “He that is washed, needeth not save to wash his feet.” The feet of his affections, the feet of his conversation, the steps of his daily walk. But there are multitudes that were never washed at all; they must wash head, and heart, and all; their nature and state need washing as well as their heart and life.