These words immediately follow the Shema, and the rabbis understood them as the source of the commandment to affix a mezuzah to our homes. They even debated whether a mezuzah should be affixed to a room occupied only temporarily or involuntarily. Ultimately, the rabbis ruled that the room required a mezuzah so that no one would conclude the High Priest was being confined like a prisoner rather than preparing for sacred service. These discussions reveal that the mezuzah is more than a ritual object; it signifies the sanctity of a place. So, a compromise was reached and the custom became to hang the mezuzah at an angle.