John Chrysostom — as excerpted in the Catena Aurea on Mark 2:23-28

“(non occ. sed v. Chrys. Hom. 39, in Matt) But being hungry, they ate simple food, not for pleasure, but on account of the necessity of nature. The Pharisees however, serving the figure and the shadow, accused the disciples of doing wrong. Wherefore there follows, But the Pharisees said unto him, Behold, why do they on the sabbath day that which is not lawful.”