Mezuzah מזוזה

"And you shall write them on the doorposts of your house and on your gates"—from this verse grew the mezuzah: a parchment on which a scribe writes by hand the two passages of the Shema, rolled and fixed aslant to the right doorpost. Passing by, a person touches it—and remembers whose house he lives in.

The laws of the mezuzah—which rooms require one, how it is checked, what renders the scroll unfit—are worked out in the Talmud beside the laws of tefillin, in tractate Menachot: both are written by the same scribe under the same rules. A mezuzah is checked twice in seven years.