Question: Among the 248 positive mitzvos in the Torah, which one is most often left unfulfilled?
Answer: Based on my observation, the mitzvah of mezuzah seems to be the most frequently neglected, though no comprehensive study validates this claim. The reasons for this phenomenon will be discussed below.
The title of this article conveys a profound truth: While G-d grants us countless opportunities to fulfill His commandments, it is ultimately our responsibility to choose whether to seize or lose these opportunities. If my assessment of the mezuzah is accurate, the widespread and avoidable neglect of this mitzvah is a significant spiritual loss and profound religious tragedy, particularly because it is a unique and special mitzvah.
Why Is This Mitzvah So Special?
Consider the following. Every moment that a mezuzah hangs on the door is a separate mitzvah. There are over 30 million seconds in a year. If a person lives in a home with 20 doorways for 50 years, the mitzvah of mezuzah will be fulfilled in more than 31 billion seconds. This great achievement is easily realized simply by nailing the mezuzos into the doorframes.
In addition to offering abundant moments of fulfillment, the mitzvah of mezuzah is unique, as it provides both spiritual and practical benefits. While most mitzvos are rewarded only in the World to Come, the Torah teaches that mezuzah brings blessings in this world, too, including long life for oneself and one’s children
(Devarim 11:21, as explained in Meseches Shabbos 32b), and a Divine shield of protection for the home and its inhabitants (Menachos 33b).
Non-Kosher Mezuzos
Unfortunately, these special benefits are often not realized for two primary reasons. First, many mezuzos are not kosher, and second, many mezuzos are improperly placed.
It is often assumed that most mezuzos sold in Jewish bookstores are kosher, but in reality, many are pasul (not kosher) because they are not written in accordance with Halacha. Writing a kosher mezuzah is a meticulous and time-consuming process. Each letter must be carefully formed in a beautiful calligraphic script with a quill on “klaf” (specially processed animal hide), following hundreds of detailed requirements. A competent sofer (scribe) will write a kosher mezuzah for three to four hours. In contrast, charlatans can mass-produce mezuzos on plain paper or imitation parchment for pennies and sell them for far more than they are worth. The financial incentive to sell invalid mezuzos is significant, so the market is flooded with non-kosher mezuzos. As a case in point, small mezuzos are very common. Writing a kosher mezuzah in a small font is difficult, and most such mezuzos are not kosher. Moreover, not all scribes are well-trained or possess the patience and yiras shamayim (fear of Heaven) to write mezuzos with exacting precision.
The mitzvah of mezuzah is “all or nothing”: a single improperly written, faded, or cracked letter among the mezuzah’s 713 letters renders it invalid. (Some preferred {lechatchila} methods exist for writing certain letters; if not followed, the mezuzah is still kosher {b’dieved}, though these mezuzos are less ideal and should not be purchased. When we say a mezuzah is invalidated by one defect, we refer only to essential requirements.) The Talmud (Menachos 29a) underscores this point, stating that even if the smallest letter, the yud, is missing a kotz (a slight stroke required by Halacha), the mezuzah is not kosher. This reflects a truism in life: neglecting small details can lead to significant consequences. This is true not only in spiritual matters but also in the physical world. Consider the Challenger space shuttle explosion in 1986. Two very small O-rings shrunk after exposure to severe cold weather and failed to seal a joint properly. This allowed hot exhaust gases to escape and catch fire during the shuttle’s ascent. The Challenger was built by a team of sophisticated experts at NASA, yet a tiny crack in a small seal led to the
destruction of the $3.2 billion spacecraft and the tragic loss of seven astronauts. Similarly, in the spiritual realm, even small imperfections in a mezuzah can render it invalid and ineffective.
Even if a mezuzah is kosher when purchased, it can deteriorate over time, as letters may fade or crack, invalidating it. For this reason, Halacha recommends having mezuzos checked by a competent sofer twice every seven years.
Unfortunately, many people do not understand the importance and value of a mezuzah, nor do they appreciate the skill, precision, and time required to create a kosher mezuzah.
I have seen people shopping for mezuzos, shocked by the price and asking, “Don’t you have anything cheaper?” Today (August 2025), purchasing a kosher mezuzah for less than $130 is nearly impossible. This is a fair price, considering that the sofer spends about four hours writing each mezuzah, and both the distributor and store owner must also make a small profit. Mezuzos are a great investment, offering longevity and security for a relatively small sum. Ironically, the same person who says, “What could be wrong with a $30 mezuzah?” might invest in an expensive home security system, forgetting the wise counsel of David Hamelech, “If Hashem will not protect a city, in vain does the watchman keep vigil.” (Tehillim 127:1)
OU Mezuzah Initiative
The Orthodox Union’s (OU) certification of mezuzos provides an invaluable service to the Jewish community. Years ago, people assumed they could determine that food was kosher by simply reading ingredient labels. In truth, ingredients like glycerin, polysorbates, and magnesium stearate—though seemingly innocuous—can be animal-derived and non-kosher. The OU’s kosher supervision program not only made kosher food widely available, but it also educated the public about the complexities of kashrus. Similarly, by certifying mezuzos, the OU will hopefully promote a deeper appreciation of the complexities of producing a kosher mezuzah, and an awareness that mezuzos should not be purchased without rabbinic endorsement or supervision of the sofer.
A Mezuzah in the Wrong Place
Halacha is very specific about where a mezuzah should be positioned, and often, mezuzas are improperly situated. Even the most beautiful, kosher mezuzah has no value if wrongly placed; the mitzvah will be unfulfilled, and the powerful spiritual qualities of a mezuzah will be unrealized.
Posting a mezuzah in the wrong location is like purchasing an expensive home alarm security system and then leaving the alarm on the dining room table instead of connecting the system to the doors and windows. A disconnected alarm system is meaningless. Similarly, not connecting the mezuzah to the proper doorway is no better than having no mezuzah at all.
One might wonder why hanging a mezuzah properly is so challenging. Isn’t it a simple matter to attach a mezuzah to a doorframe? But the reality is far more complex. Just as the laws governing the writing of mezuzos are intricate, so are the laws regarding their proper placement.
To illustrate, as a congregational rabbi for over 40 years, I made it a point to review the placement of mezuzos whenever I visited a home for a simcha or shiva call. Nearly every time I checked, I found errors in their location.
Who Will Be Your Expert?
Unfortunately, people who are unaware of the complexity of the matter place their mezuzos on the doorframe without seeking Rabbinic consultation. Most individuals who are not sofrim would never attempt to review the contents of the mezuzah scroll, yet they mistakenly believe that mounting a mezuzah is a simple matter. In my humble opinion, arranging an in-house inspection by an expert in this area of Halacha is essential to ensure mezuzos are properly positioned. Just as one must periodically have a sofer review the letters of the mezuzah to ensure they are written properly, an expert Torah scholar should verify that the mezuzos are positioned according to Halachic guidelines. This is a specialized area of Halacha that even many talmidai chachomim have not fully mastered. The numerous requirements for the placement of mezuzos are rooted in Talmudic discussions in the tractates Yoma and Menachos and codified in multiple chapters of Shulchan Aruch, Yoreh Deah. Contemporary responsa from leading poskim of the last century also address many modern home design situations. Only those who have mastered this area of Halacha can determine and recommend the appropriate locations for mezuzos.
In Conclusion: Seizing the Moment
A mezuzah is a powerful mitzvah. When fulfilled properly, it offers protection and brings blessings in this world and the next. However, if the mezuzah is invalid (posul) or incorrectly placed, it becomes an opportunity lost. The mitzvah is not fulfilled, and the spiritual rewards of security and longevity are forfeited.
Missed opportunities are a serious matter. The Talmud (Sukkah 52a) relates that at the end of time, G-d will slaughter the yetzer horah (evil inclination). Many individuals will cry in anguish as they reflect on the spiritual opportunities they failed to seize, realizing that they could have overcome the yetzer horah and achieved so much more in their lifetime with just a bit more effort.
In 1970, I had the great fortune to study in the Mirrer Yeshiva in Yerushalayim, where I listened to the phenomenal sichos mussar (moral discourses) of the great Rosh Yeshiva (head of the Yeshiva), Rav Chaim Shmulevitz, zt”l. Rav Chaim often spoke about the tragedy of missed opportunities. In one particularly moving discourse, he explained a challenging Talmudic passage (Avodah Zarah 17a). The Gemara relates the story of Eliezer ben Durdaya, who spent his entire life pursuing indulgence and sin. In a moment of profound remorse, he cried out to Hashem with such fervor that his soul departed, and he expired. A Divine voice declared, “Rav Elazar ben Durdaya is destined for life in the world to come.” When Rebbi (Rabbi Yehuda HaNasi) heard this, he wept and said, “There are those who acquire their share in the world to come bisho’ah achas (in a single hour), and there are those who acquire their share in the world to come over many years.”
Rav Chaim questioned why Rebbi cried. Wouldn’t it have been more fitting to celebrate Rav Elazar ben Durdaya’s remarkable self-transformation in a short time and his place in the world to come?
Rav Chaim explained that Rebbi wept because Rav Elazar ben Durdaya demonstrated how much could be achieved in a single hour. Like Rav Elazar ben Durdaya, everyone has the potential to achieve greatness in brief moments, yet these precious opportunities are rarely utilized. Rebbi cried because he lamented the tragic failure of most people to make full use of the immense potential that time offers and provides. (See Sichos Musar, page 124)
Every moral person laments lost opportunities in the past and wishes they could turn the clock back and have another chance. I, too, wish I could go back in time and relive my year in the Mirrer Yeshiva once again. Rav Chaim Shmulevitz was an Adam Gadol (Torah giant). Unfortunately, at age 20, I was so intimidated by Rav Chaim’s towering greatness that I was afraid to converse with him. Rav Chaim profoundly influenced me, but there was so much more I could have learned from my Rebbi if I had a personal relationship with him. Alas, the past is gone forever, and never will it return again.
In the world to come, many souls will be shocked to discover that their mezuzos were not kosher or were mounted improperly. No doubt, the realization that the chance to fulfill this beautiful mitzvah millions or billions of times was lost forever, never again to reappear, will be a source of great anguish and pain. We, the living, are in a much better position. Though we cannot recapture the past, the future remains within our reach, and we can take corrective action now. But we must act swiftly, for if we tardy even a sho’ah achas (one hour), thousands of mezuzah mitzvos may disappear into the dustbin of the irreversible past. Let’s seize the moment now and take corrective action, thereby reaping the boundless rewards of this extraordinary and incredible mitzvah.