The Mezuzah on the Right Side Corresponds to Yaakov Avinu
I would like to propose a praiseworthy explanation for the three-pronged rationale Chazal teach us regarding the mitzvah of mezuzah: (1) It protects the people of a household from harmful, negative occurrences, (2) it portends long-life, and (3) the sacred name שד"י is inscribed on its external surface for protection. As we have learned in the Gemara (Menachos 34a), the mitzvah dictates that the mezuzah be placed on the right side of the entryway as one enters the house. This is deduced from the words of the passuk: "וכתבתם על מזוזות ביתך"—and write them on the doorposts of your house. They expounded on the word "ביתך"—your house—that it be interpreted as "ביאתך"—the way a person enters his house; it should be on his right, because most people begin to walk from a stationary position by moving their right leg first.
Now, in parshas Bo, it is written (Shemos 12, 22): "ולקחתם אגודת אזוב וטבלתם בדם אשר בסף והגעתם אל המשקוף ואל שתי המזוזות...ועבר ה' לנגוף את מצרים וראה את הדם על המשקוף ועל שתי המזוזות, ופסח ה' על הפתח ולא יתן המשחית לבוא אל בתיכם לנגוף". You shall take a bundle of hyssop and dip it into the blood that is in the basin and touch the lintel and the two doorposts . . . Hashem will pass through to smite Egypt, and He will see the blood that is on the lintel and the two doorposts; and Hashem will skip over the entrance and He will not permit the destroyer to enter your homes to smite. We find the following exposition in the Midrash (S.R. 17, 3): “And touch the lintel” in the merit of Avraham; “and the two doorposts” in the merit of Yitzchak and Yaakov; and in their (combined) merit, He will see the blood “and He will not permit the destroyer.”
Thus, we learn from the Midrash that the two doorposts at the entrance correspond to Yitzchak Avinu and Yaakov Avinu. But this raises an interesting and provocative question: Which doorpost corresponds to Yitzchak, and which one corresponds to Yaakov? Based on this determination, we can determine whether the mitzvah of mezuzah, which is affixed to the right doorpost, is associated with Yitzchak Avinu or Yaakov Avinu.
After researching the matter, I found an answer in the sacred teachings of the Ma’aseh Rokeiach (Korach). He cites the aforementioned Midrash and comments: Most certainly the fact that the mezuzah is affixed to the right side corresponds to Yaakov; for, it is known to kabbalists that Yaakov’s midah is “Tiferes,” which tends to the right; whereas Yitzchak corresponds to the left doorpost, representing “gevurah.” Thus, we have a definitive answer that the placement of the mezuzah on the right doorpost is associated with Yaakov Avinu.
