Adam Clarke on Matthew 12:2

Thy disciples do that which is not lawful to do - The Jews were so superstitious, concerning the observance of the Sabbath, that in their wars with Antiochus Epiphanes, and the Romans, they thought it a crime even to attempt to defend themselves on the Sabbath: when their enemies observed this, they deterred their operations to that day. It was through this, that Pompey was enabled to take Jerusalem. Dion. Cass. lib. xxxvi.

Those who know not the spirit and design of the divine law are often superstitious to inhumanity, and indulgent to impiety. An intolerant and censorious spirit in religion is one of the greatest curses a man can well fall under.