John Calvin on Colossians 4:15

When he speaks of the Church which was in the house of Nymphas, let us bear in mind, that, in the instance of one household, a rule is laid down as to what it becomes all Christian households to be — that they be so many little Churches. See Calvin on the Corinthians, vol. 2, p. 78. Let every one, therefore, know that this charge is laid upon him — that he is to train up his house in the fear of the Lord, to keep it under a holy discipline, and, in fine, to form in it the likeness of a Church.