Jesus: Lord of the Sabbath

"Or have you not read in the Law, that on the Sabbath the priests in the temple break the Sabbath, and are innocent? But I say to you, that something greater than the temple is here" (Matthew 12:5–6).

Jesus did not have to explain what He meant by saying that on the Sabbath the priests in the temple break the Sabbath. The Pharisees had often read in the Law that priests not only were allowed but required to do many things on the Sabbath that otherwise would have violated God’s Law of rest, not to mention rabbinic tradition. . . .

http://www.macarthurcommentaries.com