In earning his living, the Muslim should stick to rules of Shari`ah and he should exert efforts in searching for the Halal and steer clear of all what is Haram.
In his well-known book, The Lawful and the Prohibited in Islam, the outstanding Muslim scholar, Sheikh Yusuf Al-Qaradawi, points out the prohibited types of employment, as follows: “The permissibility of working as an employee of a government, organization, or individual, excludes those jobs which are injurious to the cause of Islam or harmful to Muslims. Accordingly, it is not permissible for a Muslim to be an officer or soldier in an army that is fighting against Muslims, to work in a corporation or factory that manufactures armaments used against Muslims, nor in an organization which is hostile to Islam and fights its adherents. Similarly, any service rendered in support of injustice or in promoting what is Haram is itself Haram. For example, it is prohibited to work in an organization that deals in interest, a bar, a liquor shop, a nightclub, and a dance hall, etc.
It is not a valid excuse to say that one is not using what is Haram or being directly involved in it. It is a basic principle of Islam that whatever aids and assists the Haram is itself Haram. For this reason, the Prophet, peace and blessings be on him, cursed the person who writes the document of interest and the person who witnesses it, as well as the person who consumes it. Similarly, the person who serves the wine is cursed, so too is the one who serves it, and the one who drinks it.
Again, under the compulsion of unavoidable necessity, one may seek temporary employment in such companies to the extent of what is required. But, he should in the meantime search for other employment until Allah provides an alternative for him. Allah opens the door for those who sincerely try to avoid what is Haram. One must always to be on guard against temptation, which may lead him towards doubtful matters weakening his faith and compromising his religion. This is in spite of how large a profit or gain is involved. The Prophet, peace and blessings be on him said, “Leave alone what puts you in doubt and turn toward what does not put you in doubt.” (Reported by Ahmad, Al-Tirmidhi, An-Nisa’i, Al- Hakim, and Ibn Hibban)
He also said, “A person does not reach the rank of the God-fearing (Muttaqeen) until he abandons what is harmless out of fear that it may be harmful.” (Reported by Al-Tirmidhi)”
Prof. Su`aad Abdullah Saleh, head of Jurisprudence Department, Al-Azhar University, adds:
“Tobacco is Haram because it causes a lot of harm. Accordingly, working in tobacco companies is Haram for it assists in spreading and producing a Haram thing. As for working in a tobacco company with the intention of getting experience in the field of marking, it is forbidden. There are, of course, a lot of companies where one can get experience in the field of marketing without getting involved in Haram work.”