Mezuzah (מְזוּזָה)
From http://www.jewfaq.org/signs.htm (with edited) And you shall write [the words that I command you today] on the doorposts of your house and on your gates. -Deuteronomy 6:9, 11:19 On the doorposts of traditional Jewish homes (and many not-so-traditional homes!), you will find a small case like the one pictured at left. This case is commonly known as a mezuzah (Heb.: doorpost), because it is placed upon the doorposts of the house. The mezuzah is not, as some suppose, a good-luck charm, nor does it have any connection with the lamb's blood placed on the doorposts in Egypt. Rather, it is a constant reminder of G-d's presence and G-d's mitzvot. The mitzvah to place mezuzot on the doorposts of our houses is derived from Deut. 6:4-9, a passage commonly known as theShema (Heb: Hear, from the first word of the passage). In that passage, G-d commands us to keep His words constantly in our minds and in our hearts by (among other things) writing them on the ...