John Chrysostom

"And they continued" it is written, "steadfastly in the doctrine" (or, "teaching") "of the Apostles": for it was not for one day, no nor for two or three days that they were under teaching as being persons who had gone over to a different course of life. "And they continued with one accord in the Apostles' doctrine," etc. The expression is not "together," but "with one accord," ("and daily," he says afterwards, "they were continuing with one accord in the temple,") i.e. with one soul.

Homily on Acts 7 ↗

Cassiodorus

"And they were persevering in the doctrine of the apostles," etc. As those who had converted continued devoutly in the doctrine that they had embraced, and as the apostles frequently performed great miracles, the fear of the Lord and the number of the faithful people increased daily. There was great concord among the believers, such that everyone would sell their own possessions and a brother would unfailingly be provided with whatever he stood in need of. Great also was their devotion to meeting in the temple. …

Complexiones on the Acts of the Apostles ↗