בס''ד
1. “A person should always dwell in Eretz Yisrael, even in a city inhabited mostly by heathens, and he should not dwell outside the Land, even in a city inhabited mostly by Jews, for anyone who dwells in Eretz Yisrael is like one who has a God, and anyone who dwells outside the Land is like one who has no God” (Ketuvot 110b)
2. “You shall possess the Land and dwell in it, for to you have I given the Land to possess it” (Bamidbar, 33:53) [Numbers]
3. “You shall possess it and you shall dwell therein” (Devarim, 11:31) [Deuteronomy]
4. “We were commanded to take possession of the Land that God, may He be blessed, gave to our forefathers, Avraham, Yitzchak, and Yaakov; and we must not leave it in the hands of any other nation or let it remain desolate” (Addendum to Rambam’s Sefer HaMitzvot, Positive Commandment 4).
5. Chazal lavished praise upon the mitzvah of Yishuv HaAretz, going so far as to say that it is equal to all the mitzvot of the Torah (Sifrei, Re’eh 53).
6. Chazal comment on several other mitzvot that they are equal to all the rest (circumcision – Nedarim 32a; charity – Bava Batra 9a; tzitzit – Shevuot 29a; tefillin – Menachot 43b; Shabbat – Yerushalmi Nedarim 3:9; Torah study – Peah 1:1; acts of kindness – ibid.). Nonetheless, from a halachic standpoint, Yishuv HaAretz takes precedence over them all, for it is the only one that overrides a rabbinic injunction relating to the Sabbath (a “shevut”). If someone needs to violate a shevut in order to perform a brit milah (circumcision) on Shabbat, we postpone the brit instead of violating the shevut. For the sake of Yishuv HaAretz, however, the Rabbis allow one to purchase a home in Eretz Yisrael on the Sabbath, if necessary, even if this entails violating the shevut of amirah le’nachri (telling a non-Jew to do work for you on Shabbat), as the Talmud states in Gittin 8b and Bava Kama 80b (with Tosafot)
7. The reason the Rambam does not include this mitzvah in his count of the 613 is that it is beyond the regular “value” of mitzvot; therefore, it is not included in their detailed enumeration. This coincides with the rules the Rambam lays down at the beginning of Sefer HaMitzvot, stating it is inappropriate to reckon commandments that encompass the entire Torah, as he writes in Mitzvah #153 [that settling the Land of Israel is all-inclusive].