Deuteronomy 23:25
23 Whatever you vow, you must be careful to do what you have promised, such as what you have vowed to the Lord your God as a freewill offering. 24 When you enter the vineyard of your neighbor you may eat as many grapes as you please, but you must not take away any in a container. 25 When you go into the ripe grain fields of your neighbor you may pluck off the kernels with your hand, but you must not use a sickle on your neighbor’s ripe grain.
Matthew 12:1
1 At that time Jesus went through the grain fields on a Sabbath. His disciples were hungry, and they began to pick heads of wheat and eat them. 2 But when the Pharisees saw this they said to him, “Look, your disciples are doing what is against the law to do on the Sabbath.” 3 He said to them, “Haven’t you read what David did when he and his companions were hungry—
Notes and References
"... The controversy begins with Jesus and his disciples walking through a grain field on the Sabbath and the disciples, not Jesus, pick and eat grain. Matthew omits “made a way” (ὁδὸν ποιεῖν) from Mark. Perhaps it is distracting from the main halakic issue at hand (i.e., mercy for the hungry on the Sabbath). “ὁδὸν ποιεῖν” could possibly be construed as doing work, and Matthew is only concerned with justifying the disciples’ act of picking grain on the Sabbath. While Deuteronomy 23:25 permits gleaning by hand in a neighbour’s grain field, it makes no such allowance on the Sabbath. Matthew, however, adds to his Markan source that the disciples were “hungry” (ἐπείνασαν). It is on this point that the Matthean Jesus’ builds his halakic argument. Seeing the disciples glean the grain field, the Pharisees accuse them of doing what is not lawful/permissible (ἔξεστιν) on the Sabbath. Here, for the first time in the narrative, they make their objection directly to Jesus. He is responsible for the actions of his followers. First-century Sabbath interpretation is diverse, but mentioning the detail about the disciples’ hunger shows Matthew concedes that the Pharisees’ accusation that the disciples are working has some merit. Indeed, the Matthean Jesus’ following response implies this as well. However, Jesus will argue that there are certain circumstances for work and types of work that are permissible on the Sabbath, of which, his disciples’ grain picking is one. Jesus never abolishes or disregards the Torah, rather, like many Second Temple authors, he develops and grows Torah tradition by explaining and declaring what constitutes permissible work on the Sabbath ..."
Stiles, Steven J. Jesus' Fulfilment of the Torah and Prophets: Inherited Writing Strategies and Torah Interpretation in Matthew's Gospel (pp. 176-177) The University of Edinburgh, 2017