Two views of whether the disciples violated the sabbath laws when they plucked the heads of grain:
Yes, they did so as they were on a journey of service that apparently was long enough to need sustenance, so Jesus makes the analogy to the journey of service that David and those who were with him made when they ate of the consecrated bread (1 Samuel 21:3–6). The disciples knew the law that it is not lawful to prepare a meal on the Sabbath. When you pluck heads of grain, you engage in harvest in a limited way, thus engaging in the preparation of food.
Walking through the fields was not seen as a violation of the Sabbath. The phrase
‘went… through
does not imply formally undertaking a journey, since it was the Sabbath. The law allowed the plucking of ears of grain (Deuteronomy 23:25), but in Jewish tradition it was forbidden on the Sabbath, as a form of harvesting or preparing a meal—both of which were prohibited.
Interpretation 1:
Yes, they did so as they engaged in a journey of service for which they had to exert themselves, and apparently the journey was sufficiently long that they had need of sustenance. Because Jesus’ journey of service made some demands on his disciples, it becomes possible to refer to the journey of service that David and those who were with him made when they ate of the consecrated bread (1 Samuel 21:3–6). The disciples begin to pluck the heads of grain and to eat the kernels. They know the law: that it is not lawful to prepare a meal on the Sabbath. When you pluck heads of grain, you engage in harvest in a very limited way, meaning that you engage in the preparation of food. We should not think that they did so thoughtlessly. Their hunger must have been quite significant before they began to satisfy it by transgressing the Sabbath commandment.1
Interpretation 2:
No, we do not read that merely walking through the fields was already regarded as a violation of the Sabbath. The phrase went… through
does not indicate formally undertaking a journey, since it was the Sabbath. The law itself permitted the plucking of ears of grain, as in Deuteronomy 23:25: If you go into your neighbour’s standing grain, you may pluck the ears with your hand, but you shall not put a sickle to your neighbour’s standing grain.
2
The plucking of grain along the way was permitted by the law (Deuteronomy 23:25). Yet according to Jewish tradition it was forbidden on the Sabbath. It was regarded as a form of harvesting or of preparing a meal—both of which were prohibited.3
2 Les pharisiens, voyant cela, lui dirent: Voici, tes disciples font ce qu'il n'est pas permis de faire pendant le sabbat.