Fatwa

[...] migrating from the land of the Infidel to the Land of Islam is an obligation and this up until the Day of Judgment.

[...] Dwelling among the infidel... is forbidden... because of all the debasement and blemish or spiritual and vital ruin it can cause.

Quoted in Al-Nawchariçi, Al-miaar al-mouarib, Beirut, 1981, p.119-124