What is the ruling on a Muslim traveling to non-Muslim countries for the purpose of seeking sustenance and improving living conditions, with the intention of permanent settlement and non-return, and what is the opinion of the four imams on this matter?

The early Imams did not address the issue of a Muslim's emigration to lands of disbelief for residence, as this situation did not occur in their time. However, its ruling can be inferred from the issue of emigration from Dar al-Harb (Abode of War) to Dar al-Islam (Abode of Islam). Whoever obligates the former would prohibit the inverse.

Ibn Rushd and al-Wansharisi held the view that it is obligatory for a Muslim to emigrate from Dar al-Harb to Dar al-Islam, and they condemned the permissibility of entering lands of disbelief. Al-Wansharisi argued that the scenario of residence befalling Islam (the current question) is not essentially different from the scenario of Islam befalling residence in Dar al-Harb.

As for the various schools of jurisprudence: the Shafi'is and Hanbalis permit residence in Dar al-Kufr (Abode of Disbelief) if the Muslim is able to openly practice their religion and is safe from temptation, though emigration is considered preferable. The Hanafis, on the other hand, believe that the obligation of emigration was abrogated with the conquest of Mecca. As for the Malikis, they hold that emigration from Dar al-Kufr is obligatory, as transmitted by Ibn Rushd and al-Wansharisi.

In summary, the original ruling regarding residence in lands of disbelief is prohibition (according to the Malikis and Ibn Hazm). However, the majority of jurists (Hanafis, Shafi'is, Hanbalis, and some Malikis) permit it if the Muslim is safe regarding their religion, self, and property, and is able to openly practice the rituals of their religion.