הלכה אויף רות 1:5

It is forbidden to leave Eretz Yisroel, ever, except for purposes of learning Torah or marrying or to save (his money) from the non-Jews. Then he must return to the Land. One may leave for commerce. However, one may not reside (permanently)³³Without intention of returning. outside of the Land unless there is famine so severe that wheat which once cost one Dinar now costs two Dinars. This rule applies when people have money and the fruit is expensive. However, if fruit is cheap, but people have no money or income, and he doesn’t even have a cent in his pocket, one may go to wherever he can to make a living³⁴Lit., make a profit.. Although it may be permissible to leave the country, it would not be “altruistic” to do so. For we see that Machlon and Kilyon, two of the greats³⁵That is, great community leaders. of their generation, left only because of the considerable troubles there were then and, nevertheless, perished.