The Torah portion of Eikev contains the commandment of mezuzah — “and you shall inscribe them on the doorposts of your house and on your gates.”1

Concerning the mitzvah of mezuzah, the Rambam writes:2 “It is obligatory to be scrupulous with regard to mezuzah … whenever he enters or leaves [his house], he will encounter the unity of His Name… He will be reminded of his love for Him and will be roused from his sleep and the errors of indulging in mundane delights. He will then know that only knowledge of G‑d is eternal; he will immediately come to his senses and follow the paths of righteousness.”

We must understand why the Rambam states “It is obligatory to be scrupulous with regard to mezuzah ” rather than using the seemingly more appropriate phrase “It is obligatory to be scrupulous with regard to the mitzvah of mezuzah ,” similar to his statement:3 “It is obligatory to be scrupulous with regard to the mitzvah of tzitzis.”

At first glance, it would seem that the Rambam’ s reason for writing “It is obligatory to be scrupulous with regard to mezuzah ,” rather than “the mitzvah of mezuzah ,” is that the mounting of mezuzah is not an obligatory mitzvah — one need not select a dwelling that is obligated to have a mezuzah so as to be able to fulfill this commandment.4

However, if this were the reason, then the phrase “it is obligatory” would seem to be out of place; the Rambam should have used the expression “One should make an effort” or the like.

It therefore seems that the Rambam is indeed referring to the mitzvah of mezuzah. This being so, why does he not state explicitly “It is obligatory to be scrupulous with regard to the mitzvah of mezuzah ”?

When the Rambam says it is obligatory to be scrupulous, he is not referring to the degree of observance, but rather is making it clear that one must be scrupulous in seeing to it that the mitzvah of mezuzah has an appropriate effect. This is why he goes on to say: “Whenever he enters or leaves [his house], he will encounter the unity of His Name … He will be reminded of his love for Him and will be roused from his sleep and the errors of indulging in mundane delights. He will then know that only knowledge of G‑d is eternal; he will immediately come to his senses and follow the paths of righteousness.”

This aspect of mezuzah is not a part of the performance of the mitzvah , for that is accomplished by merely affixing the mezuzah to the doorpost and keeping it there.5

Thus, the Rambam is describing the impact that the mezuzah is to have — the dwelling’s inhabitant should be scrupulous in seeing to it that whenever he encounters the mezuzah, “he will be reminded of his love for Him and will be roused from his sleep… and follow the paths of righteousness.”

This sheds light on another statement of the Rambam. The Rambam concludes the laws of mezuzah with the statement: “The early Sages have said:6 ‘Whoever has tefillin on his head and hand, tzitzis on his garment and a mezuzah on his entrance is assured that he will not sin, for he has many reminders… that save him from sin.’ ”

The Rambam quotes this statement only in the laws of mezuzah, and not earlier in the laws of tefillin , or later in the laws of tzitzis.

According to the above explanation, however, this seeming omission is entirely understandable, for it is the mezuzah as an object — as opposed to tefillin and tzitzis — that serves as a reminder.

As explained earlier by the Rambam ,7 it is the overall sanctity of tefillin that keeps a person from sin. With regard to tzitzis as well, the Rambam explains8 that it is the commandment of tzitzis — inasmuch as it acts as a reminder of all the commandments — that keeps a person from sin.

It is only with regard to mezuzah , possessing as it does “the unity of His Name,” that the object itself keeps one from sinning by serving as a perfect reminder.

Based on Likkutei Sichos, Vol. XXIX, pp. 61-66