When the Pharisees saw this, they said to Him, “Look, Your disciples are doing what is unlawful on the Sabbath.”
The Jewish teachers had corrupted many of the commandments, by interpreting them more loosely than they were intended; a mistake which Christ discovered and rectified (ch. 5) in his sermon on the mount: but concerning the fourth commandment, they had erred in the other extreme, and interpreted it too strictly.
Commenting on Matthew 12:1-13
But when the Pharisees saw it,.... Who went along with him, or followed him, being employed to make observation on his words and actions, they said unto him; Luke says, "unto them", the disciples: it seems, they took notice of this action both to Christ and his disciples, and first spoke of it to the one, and then to the other, or to both together...
Verse 2. Upon the sabbath day. The Pharisees, doubtless desirous of finding fault with Christ, said that, in plucking the grain on the sabbath day, they had violated the commandment. Moses had commanded the Hebrews to abstain from all servile work on the sabbath, . On any other day this would have been clearly lawful, for it was permitted, . (k) "not lawful"