Matthew 12:1-8 Jesus Is Lord Of The Sabbath.
Jesus and his disciples did travel on the Sabbath, and on this occasion they passed through a grainfield, and they plucked heads of grain as food while they walked (v. 1). The law prohibited one from taking a sickle to a neighbor’s grainfield, for this was considered stealing, but it was permitted for one to take what they needed as food for the day (Dt. 23:24-25). But this law does not deal specifically with the Sabbath. Presumably the Pharisees did not have an issue with what they were doing per se, but that it was done on the Sabbath (v. 2). Jesus does not dispute that what they were doing was not lawful to do on the Sabbath, for his main point here was to teach that he was Lord of the Sabbath (v. 8).
To this end he appeals also to precedence, as with the case of David and his men, who out of the necessity for food did that which was not strictly lawful, whether on the Sabbath or not (v. 3a Cf. I Sam. 21:6). The show bread was only to be consumed by the priests (v. 3b Cf. Ex. 29:32; Lev. 24:5-9). It is important to note that David only took six loaves of the showbread, leaving six for the priests. Eating is what the puritans called a work of necessity, even as the priests had work to do on the Sabbath as ministers in the tabernacle/temple (v. 5 Cf. Nu. 28:9). Finally, Jesus makes the point that he was greater than the temple (v. 6 Cf. Is. 66:1-2). This was besides the point that works of mercy were also greater than the sacrifices.