In presenting the laws relevant to a Jewish king, the Torah in Parashat Shoftim (17:16) commands that the king may not have extra horses, as this might result in his sending men to reside in Egypt to breed horses. The Torah in this context mentions that it is forbidden to return to Egypt, a prohibition which the Sefer Ha’hinuch lists as one of the 613 Biblical commands. This prohibition appears already earlier, in Parashat Beshalah (Shemot 14:13), and later, in Parashat Ki-Tabo (28:68).
The Sefer Ha’hinuch writes that this command refers to permanently residing in Egypt. The Torah forbids permanent residence in Egypt, the Sefer Ha’hinuch explains, because ancient Egypt was an especially immoral society, and Hashem specifically took us away from Egypt so that we will not adopt its people’s conduct, and we will thereby be worthy of His blessings. He therefore forbade us from returning to Egypt, so that we do not embrace their beliefs or practices.
This command applies in all times, and is binding upon both men and women. The Sefer Ha’hinuch writes that one who transgresses this prohibition by residing in Egypt is not liable to Malkut. Although going to Egypt obviously involves a concrete action, nevertheless, the violation is committed not by going to Egypt, but rather through the decision to permanently reside there. Therefore, this prohibition falls under the category of “Lav She’en Bo Ma’aseh” – prohibitions that are violated without a concrete action, which are not punishable by Malkut.
The Rambam writes in Hilchot Melachim that if a Jewish king conquers Egypt and annexes the territory, making it part of Eretz Yisrael, then it would become permissible to live there. Since the territory of Egypt would then be considered part of the Land of Israel, the prohibition would not apply.
Many writers raised the question of why many pious Jews lived in Egypt throughout the ages. Thriving, Torah-committed Jewish communities existed in Cairo, Alexandria and other Egyptian cities, despite this Biblical prohibition. In fact, the Rambam, who discusses this command in his writings, lived in Egypt.
One answer given is that, as the Sages mentioned in various contexts, the Assyrian emperor Sanherib conquered the entire region and moved the populations from one country to another. Therefore, the people living in Egypt since the Assyrian conquest were not the ancient Egyptians spoken of by the Torah. If we assume that the prohibition against living in Egypt is linked not to the geographical territory of Egypt, but rather to its people, then the prohibition perhaps no longer applied after Sanherib conquered Egypt and forced its people into exile.
This approach, however, seems difficult to accept, as the Torah says that one may not live in Egypt, without making any mention of the people of Egypt.
Others note that the Torah formulates this command as a prohibition against returning to Egypt the way our ancestors left. It appears from the text that the Torah forbids not living in Egypt per se, but rather returning there from the Land of Israel. Therefore, going to live there via some other route would be permissible.
Yet another theory is that this prohibition applies only when Am Yisrael lives in its homeland, but not during exile. Therefore, it was permissible for Jews to live in Egypt during the centuries of our nation’s exile.
By contrast, there are those who maintain that it is indeed forbidden to live in Egypt at any time, and regardless of the route taken to arrive there, but the Rambam was compelled to live in Egypt. He served as the personal physician of the Sultan in Egypt, and thus had no choice but to remain in the country. Additionally, the Rambam went to Egypt to lead the Jewish community there, to help them and guide them spiritually, and this important Misva may perhaps override the prohibition against residing in Egypt.
Interestingly, it is said that the Rambam signed some of his letters with his name and the addition, “who transgresses three prohibitions each day,” referring to three times the Torah forbids living in Egypt. It seems likely that if there was no justification for living there, the Rambam would not have remained. Quite obviously, a man as righteous as the Rambam would not knowingly transgress a Biblical command. It seems that the Rambam felt compelled by circumstance to remain in Egypt, as discussed, and he made this note to lament the fact that he needed to live there, and to express his longing to live in Eretz Yisrael.