Musar sobre Deuteronómio 11:20

One recites the blessing, "Blessed are You, Lord our God, King of the Universe, who sanctified us with His commandments and commanded us to affix the mezuzah." And one must place it on the right, as it is stated: And you shall write them on the doorposts of your house (beitecha) and in your gates — the way you enter (biatecha). And when a person lifts his foot [to begin walking], he lifts his right foot first (Yoma 11b:9). And all entrances are obligated in [having] a mezuzah, except for entrances that are not the way of respect [such as bathrooms]. And it is the obligation of the one living in the house to place a mezuzah. As Rav Mesharshiyah said, "Affixing a mezuzah is the obligation of the resident." And that is even though the house is not his, but only rented by him. And when he leaves, he may not take it in his hand and leave; rather, he must leave it there. And this is the case if a Jew will [replace him] in the house. But if a gentile [will replace him], he may take it and leave. As we follow the textual version in Bava Metzia (102a:2) in the chapter [entitled] HaShoel: Come and hear — One who rents out a house to his fellow, it is incumbent upon the renter to prepare a mezuzah for it. And when he leaves, he may not take it in his hand and leave. But if it is [the house of] a gentile, he may take it in his hand and leave. And there was an incident in which a renter took his mezuzah in his hand and left; and he buried his wife and two sons. And we follow the textual version in the chapter [entitled] BeMeh Madlikin (Shabbat 32b): For the sin of mezuzah do a person's sons and daughters die when they are young, as it is stated: the blood of the souls of the innocent poor (Jeremiah 2:34), and next to it is: you did not find them breaking in. The understanding is that because they made entrances like a thief’s breach, without a mezuzah, their innocent poor, who are one's sons and daughters, died. And we place them at the entrance on the outside. For the attribute of the Holy One, blessed be He, is not like the attribute of a king of flesh and blood. The attribute of flesh and blood is that a king lays down inside his room, and his servants protect him from the outside, whereas the Jewish people, who are the servants of the Holy One, blessed be He — as it is stated: For it is to Me that the children of Israel are servants (Leviticus 25:55) — lay down inside, and the Holy One, blessed be He protects them from the outside. As it is stated: The Lord is your keeper, the Lord is your shade upon your right hand. The Lord will guard your going and coming now and forever (Psalms 121:5, 8).

It is also written in Sifra DiShelomo HaMelech (Zohar, ibid.) that a certain demon rests beside the entrance of one’s home, waiting to cause harm to whoever enters. But when this demon sees the name “A-lmighty” inscribed upon the mezuzuah he is prevented from causing harm. It follows that one should not pour out foul water near the mezuzah for two reasons: First, in order not to show contempt for the holy name of the Master of the Universe. And second, lest the demon that is there be allowed to cause harm, Heaven forbid. But if the environment of the mezuzah is clean and the person shows his affection towards it by kissing it as he goes in and out, the demon is compelled to bless him, saying, “This is the gate of Hashem, let the righteous enter it” (Tehillim 118:20). On the other hand, if a person does not have a mezuzah at the entrance to his home at all, then the demon has permission to cause harm. Woe to the owner of the house for showing concern over the small sum that it would cost to purchase a mezuzah but not for his own welfare! Children, in particular, die of a disease called rablis if there is not a proper mezuzah in every room of the house. For this reason these two verses are adjacent to one another in the Torah: “And you shall write them upon the doorposts [mezuzos] of your house and upon your gates” (Devarim 11:20), and, “In order that your days and the days of your children shall be increased” (ibid. 21). Similarly, in Maseches Shabbos (32b) the Sages of blessed memory proclaim that children die young on account of the neglect of the mitzvos of mezuzah and tzitzis. Supervision of this matter is the duty of the rabbis and the heads of the community. Whoever is meticulous about it will merit the fulfillment of the verse, “Fortunate is the man who listens to Me…to guard the doorposts of My entrances, for whoever finds Me finds life” (Mishlei 8:34-35). And may that life be long, Amein.