Rabbi Yitzchak ben Sheishes, the Rivash (1326-1408)

In the course of a discussion about undertaking a journey to Eretz Yisroel that will involve violating Shabbos, the Rivash writes: "We have established that for a mitzvah one is permitted to depart even on a Friday, and there is no doubt that traveling to Eretz Yisroel is a mitzvah. Our Sages have said, "Whoever lives outside the Holy Land is like one who has no G-d" (Kesubos 110b). And they said further, "Whoever walks four cubits in Eretz Yisroel is guaranteed a share in the World to Come" (Kesubos 111a). Although the prophet said to the exiled Jews, "Build houses and live in them" (Yirmiyah 29:5), that was only because exile was decreed upon them, and the One who exiled them did not permit them to return, until they returned with the permission of Cyrus. And now as well, one of the Three Oaths G-d made the Jewish people swear is not to go up as a wall." (Shailos Uteshuvos Rivash, siman 101)