What is the ruling on working in the lands of the disbelievers?

It is forbidden for a Muslim to reside in a land of disbelief for work if he cannot perform the rituals of his religion and fears temptation, due to the Prophet's (PBUH) saying: "I am free of any Muslim who resides among polytheists." It is not permissible to emigrate there except out of urgent necessity or for the purpose of da'wah (inviting to Islam), provided there is a strong presumption of safety from falling into what displeases Allah.