Mezuzah: More Than a Symbol on the Doorpost

In the language of the Torah, the word mezuzah refers to one of the doorpost sides of a house or room. Today, however, it commonly refers to a sacred object, a scroll inscribed with the biblical passages of Shema Yisrael and Vehaya Im Shamoa, written in Ashuri script, the same script used in Torah scrolls.

The scroll is rolled from end to beginning and wrapped (typically in plastic) to protect it from the elements. It is then placed inside a mezuzah case, made of materials such as plastic, metal, or wood, and affixed to the doorpost of a home. Mezuzahs come in various sizes, but those who are meticulous about mitzvah observance typically prefer larger scrolls since small scrolls have minuscule letters, which can raise concerns about halachic validity (Jewish legal validity).

Why We Affix a Mezuzah

The commandment to affix a mezuzah comes from the very words written within the scroll: “And you shall write them on the doorposts of your house and on your gates” (Deuteronomy 6:9; 11:20). The sages explain that the purpose of this mitzvah is to serve as a constant reminder about the oneness of God and the principle of Divine reward and punishment.  Whenever we leave or return home, the small scroll affixed to our doorpost will remind us of these foundational principles of Judaism.

In rabbinic literature, the mezuzah is listed alongside tzitzit and tefillin as one of the identifying signs of a Jew. Moreover, these three mitzvot (commandments) also function as spiritual safeguards against sin. Those who neglect the mitzvah of mezuzah, the sages say, are counted among the seven individuals distanced from Heaven.

It is customary in many communities to kiss the mezuzah when entering or exiting the door as an expression of love for the mitzvah.

A Reminder and a Protection

Halacha (Jewish law) mandates that mezuzot be checked twice every seven years to ensure their continued validity. Still, many people associate mezuzot with personal well-being, and during times of crisis or hardship, be it financial or medical, they often check their mezuzot for possible damage or flaws.

Indeed, rabbinic sources link the mezuzah to Divine protection. One such story tells of Onkelos the convert, who, when questioned by Roman officials sent to arrest him, was asked why he kissed the mezuzah. He replied: “The custom of the world is that the king stays inside while his guards protect him from the outside. But the Holy One, blessed be He, His servants remain inside while He protects them from the outside.”

It is customary to inscribe the Hebrew letters shin, daled, and yud, Shaddai, on the outer part of the scroll. This is both the name of God as well as the acronym for Shomer Daltot Yisrael, “Guardian of the doors of Israel.”

The Shulchan Aruch mentions the mezuzah's protective quality, yet emphasizes that one should not perform the mitzvah for the sake of protection alone, but because it is a Divine command. Likewise, Maimonides rebukes those who treat the mezuzah like an amulet or charm: “…Fools, not only have they nullified the mitzvah, but they turn a great commandment - one affirming God’s unity, love, and service - into a talisman for personal benefit, as if it were a worldly trinket.”

The mitzvah of mezuzah remains one of the most widely observed commandments among the Jewish people. A famous example is Dr. Garrett Reisman, the first Jewish astronaut to stay aboard the International Space Station. Upon boarding the space shuttle Endeavour, he immediately affixed a mezuzah near his sleeping quarters in orbit around the Earth.