"There is no emigration after the conquest (of Makkah) لا هجرة بعد الفتح

3 - وعن عائشة رضي الله عنها قالت قال النبي صلى الله عليه و سلم : [ لا هجرة بعد الفتح ولكن جهاد ونية وإذا استنفرتم فانفروا ] متفق عليه
ومعناه : لا هجرة من مكة لأنها صارت دار إسلام.
3- A`ishah (May Allah be pleased with her) narrated that the Prophet (PBUH) said, "There is no emigration after the conquest (of Makkah) but only Jihad [(striving and fighting in the cause of Allah) will continue] and good intention.* So if you are summoned to fight, go forth.''
[Al-Bukhari and Muslim].
*. Intention according to An-Nawawi: It means that goodness which ceased to continue by the cessation of emigration can still be obtained by Jihad and by intending accomplishing good deeds.
Commentary. When a country or a region is regarded as Dar-ul-Islam (land of Islam), it is not necessary to migrate from it to some other place. It is, however, obligatory to emigrate from such regions which are Dar-ul-Kufr (land of infidels) and where it is difficult to adhere to Islamic injunctions. It is also evident from this Hadith that when it is not necessary to migrate from one Islamic country to another then it is also not permitted by the Shari`ah to leave an Islamic country to settle permanently in Dar-ul-Kufr only for the reason that the latter has plenty of wealth and social welfare. Unfortunately, Muslims today are afflicted with this disease. The transfer of their capital and talent to Dar-ul-Kufr is indeed very disturbing because on one side these two factors are lending support to the economy of Bilad-ul-Kufr (countries of infidels) and on the other, obscenity and indecency that are common in such countries, are becoming increasingly common among the Muslims too.
Another highly important reason for the prohibition of migration of Muslims to Dar-ul-Kufr is that it goes against the spirit as well as their readiness for Jihad fi sabilillah (striving and fighting in the way of Allah). This spirit and readiness must be kept always alive so that the Muslims may respond at once to the call of Jihad whenever the need for it arises anywhere.