As Jesus was passing through a field of grain on the sabbath, his disciples began to make a path while picking the heads of grain. At this the Pharisees said to him, “Look, why are they doing what is unlawful on the sabbath?” He said to them, “Have you never read what David did when he was in need and he and his companions were hungry? How he went into the house of God when Abiathar was high priest and ate the bread of offering that only the priests could lawfully eat, and shared it with his companions?” Then he said to them, “The sabbath was made for man, not man for the sabbath. That is why the Son of Man is lord even of the sabbath.”
The disciples being hungry, only ate simple food, not for pleasure, but on account of the necessity of nature. The Pharisees however, accused the disciples of doing wrong. But our Lord brings forward David, to whom it once happened to eat though it was forbidden by the law, when he touched the Priest's food, that by his example, he might do away with their accusation of the disciples.
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, etc." 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."