Theophylact of Ohrid — as excerpted in the Catena Aurea on Mark 1:21-22

“Quitting Nazareth. Now on the sabbath day, when the Scribes were gathered together, he entered into a synagogue, and taught. Wherefore there follows, And straightway on the sabbath day, having entered into the synagogue, he taught them. For for this end the Law commanded them to give themselves up to rest on the sabbath day, that they might meet together to attend to sacred reading. Again, Christ taught them by rebuke, not by flattery as did the Pharisees; wherefore it says, And they were astonished at his doctrine; for he taught them as one having power, and not as the Scribes. He taught them also in power, transforming men to good, and He threatened punishment to those who did not believe on Him.”