Bede the Venerable — as excerpted in the Catena Aurea on Mark 2:23-28

“(ubi sup.) There is, however, no discrepancy, for both were there, when David came to ask for bread, and received it: that is to say, Abimelech, the High Priest, and Abiathar his son; but Abimelech having been slain by Saul, Abiathar fled to David, and became the companion of all his exile afterwards. When he came to the throne, he himself also received the rank of High Priest, and the son became of much greater excellence than the father, and therefore was worthy to be mentioned as the High Priest, even during his fathers life-time. It goes on: And he said to them, The sabbath was made for man, and not man for the sabbath. For greater is the care to be taken of the health and life of a man, than the keeping of the sabbath. Therefore the sabbath was ordered to be observed in such a way, that, if there were a necessity, he should not be guilty, who broke the sabbath-day; therefore it was not forbidden to circumcise on the sabbath, because that was a necessary work. And the Maccabees, when necessity pressed on them, fought on the sabbath-day. Wherefore, His disciples being hungry, what was not allowed in the law became lawful through their necessity of hunger; as now, if a sick man break a fast, he is not held guilty in any way. It goes on: Therefore the Son of man is Lord, &c. As if he said, David the king is to be excused for feeding on the food of the Priests, how much more the Son of man, the true King and Priest, and Lord of the sabbath, is free from fault, for pulling ears of corn on the sabbath-day.”