When a Jew attaches a mezuzah, he entrusts his house and everyone living in it under the patronage and protection of the Almighty. The Lubavitcher Rebbe compared the mezuzah to a soldier’s helmet capable of saving a life.
A mezuzah that meets all the requirements protects the Jewish home from all negative influences. Jewish tradition says that the mezuzah protects the residents of the house, even if they are on the road.
As it is said in the Psalms (Teilim): “The Lord will keep you at your exit and at your entrance.” These are lines about the mezuzah. It is important to understand that only a mezuzah that meets all the requirements of Jewish law has such properties. If, God forbid, the mezuzah becomes unusable (for example, the letter is erased, etc.), then the mezuzah “does not work”, loses its properties. Therefore, it is very important to acquire mezuzas, the quality of which there is no doubt. There is a custom, entering and leaving, to kiss the mezuzah with love and joy. This is due to the custom of kissing a Torah Scroll.
In the mezuzah itself, the following is written: “And write them on the doorposts of your house and your gates, so that your days and the days of your sons may last on the land that …” The Almighty Himself indicates the reward for fulfilling this commandment: longevity and sustenance. For it is said, “And I will give rain to your country in due time, early and late, and you will gather your bread, and grapes, and olive oil.” Hence we teach that a person who carefully observes the commandment about the mezuzah lives for a long time.
What is said in the mezuzah covers almost all aspects of human life and applies to both the physical world and spirituality. Our sages have said many praiseworthy words about the mezuzah, because thanks to it a person receives great benefits: children, food and health. Even when a person is not busy thinking about the mezuzah, he is guarded by one of the Names of the Almighty, consisting of the letters “shin”, “dalet”, “yod” and meaning “Almighty”. This Name is usually depicted on the mezuzah. It is also perceived as an abbreviation of the words “Shomer Dlatot Israel” (Guardian of the doors of Israel).