Musar su Deuteronomio 11:20

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.