Khulwah of female
    passenger riding in taxi driven by a man
Question

                As-salamu alaikum.
      Is it halal or not for a Muslim to drive a taxi because a member of the
      opposite sex might be alone in the car with him which would be khulwah?
Praise be to Allah.The Messenger of Allaah 
 (peace and blessings of Allaah be upon him)
    said: “No man is ever alone with a woman (khulwah) but the Shaytaan is the third one
    with them.” (Reported by Ahmad and by al-Tirmidhi in his Sunan, 2091; Saheeh
    al-Jaami’, 2546). Allaah says in the story of Yoosuf, peace be
    upon him (interpretation of the meaning): “And she, in whose house he was, sought
    to seduce him (to do an evil act), she closed the doors and said, ‘Come on, O
    you’…” [Yoosuf 12:23]
    It is not permitted for a man to be alone with a woman to whom he is not
    related, whether this is in a house, office, clinic, elevator, car or any other place,
    because this may be the cause of him doing something haraam. Shaytaan is keen to tempt
    people and make them fall into haraam deeds. The fuqaha’ are agreed that khulwah or
    being alone with a woman to whom one is not related is forbidden. They said: “No man
    should be alone with a woman who is not his mahram (a close relative to whom marriage is
    forbidden) or his wife, but is a stranger to him, because the Shaytaan will whisper to
    them and tempt them to do something that is not permitted. (Al-Mawsoo’ah
    al-Fiqhiyyah, 19/267) It is not permitted for a man to be alone with a
    non-mahram woman even if he is teaching her Qur’aan, or to lead her in prayer if only
    the two of them are present. The guideline regarding khulwah is that this prohibition
    applies in any situation where their figures are hidden from other people (Fath
    al-Baari, 9/333). A taxi driver is bound to pass through empty streets
    or highways, and the structure of the car conceals most of the body of a person riding in
    it. Furthermore, there is no guarantee that a forbidden conversation will not take place,
    or that there will not be an agreement to do something forbidden. How many tragedies and
    painful stories and disasters have occurred because of a driver being alone with a female
    passenger! The wise sharee’ah of Islam has taken all precautions to avoid anything
    that may lead to wrongdoing. It is essential to completely avoid any situation where a man
    and woman who are not related may be alone together. A taxi driver should not accept a
    female passenger who is alone, except in cases of emergency such as accidents and the
    like. And Allaah is the Source of strength.