Adam Clarke on Colossians 4:15

Salute - Nymphas, and the Church - in his house - This person, and his whole family, which probably was very numerous, appear to have received the Gospel; and it seems that, for their benefit and that of his neighbors, he had opened his house for the worship of God. In those primitive times there were no consecrated places, for it was supposed that the simple setting apart of any place for the worship of God was a sufficient consecration. See of those domestic churches, Rom 16:5 (note); 1Cor 16:19 (note)