Rumor reached the sages that Rabbi Shimon ben Antipatros was in the habit of beating his dinner guests. Beating them. Not turning them away at the door, not refusing them a second helping — physically striking people who had come to share his bread.
The sages dispatched Rabbi Joshua to investigate.
Joshua arrived, was welcomed in, and found the accusation oddly true. When a guest at the table swore casually, tossing around the Name of God as filler in conversation, Rabbi Shimon rose and struck him. Again and again, at every careless oath.
Joshua asked him to explain himself.
"They swear," Rabbi Shimon said simply. "They use the Name of God as though it were a seasoning for their meat. They pepper their sentences with oaths for flavor. This is contempt for the Torah. It is contempt for the third commandment — Lo tisa et shem Adonai elohecha la-shav, 'Thou shalt not take the name of the Lord thy God in vain' (Exodus 20:7). I cannot sit at a table where the Name is dishonored and say nothing. So I say something with my hand" (Gaster, Exempla No. 103).
Joshua returned to the sages with the report. The rabbis did not recommend Shimon's method — they were not enforcers of table manners. But they understood the seriousness underneath it.
The third commandment is the only one of the ten that God insists He will not leave unpunished. Rabbi Shimon was a man who had simply decided that his own house would honor the Name with the reverence the Torah demands. His guests left, in more than one sense, with the lesson stamped on them.