Jesus heals a lame man, claims to be the son of God (and the Son of Man), explains the Sabbath to the Pharisees and even heals on the Sabbath: John 5:1–47; Mark 2:23–28; Matthew 12:1–8; Luke 6:1–5; Mark 3:1–6; Matthew 12:9–14; Luke 6:6–11; Matthew 12:15–21
As a (former) tax collector, Matthew must have been deeply aware of his own need for God’s mercy. He mentioned it in his self-titled book when writing about his first few days with Jesus, and he wrote it again when describing Jesus’ response to the Pharisees’ hardline interpretation of the scriptures.
The issue this time was what people could do on the Sabbath. Harvesting was not allowed—something that’s hard to disagree with if you think about how much work is involved in harvesting a crop, whether by hand (as in the times of Jesus) or even with a combine harvester as we do now.
But how much actual work did the disciples do when the picked a few heads of grain from a crop as they walked past? Jesus set them straight: Sure, it looks like work to you, but what about when people like King David broke the Law to feed themselves?
The Sabbath is made for people, because we need to rest, not because God wants us to starve in honour of Him:
Matthew 12:7-8 But you would not have condemned my innocent disciples [for casually picking grain to eat it] if you knew the meaning of this Scripture: ‘I want you to show mercy [love], not offer sacrifices.’ For the Son of Man is Lord, even over the Sabbath!