פירוש על עבודה זרה 99:12

The baraita distinguishes between an idolater who uses stones from a Mercurius to pave the roads, in which case a Jew can walk on the roads, and a Jew who uses these stones, in which case it is prohibited for the Jew to walk on the roads. But Rabbah b. Yirmiyah cannot explain this distinction. “Carpenter” here seems to be a nickname for a scholar, probably due to the high level of skill a carpenter needs to shape his material.