Ruling on
    Muslims and kaafirs leaving things to one another in their wills
Question

                What is the ruling on a Muslim
      leaving something to a kaafir in his will, so long as it does not exceed one-third of the
      estate? What is the ruling on the opposite, i.e., can a Muslim accept money from a kaafir
      if he leaves it to him in his will?
Praise be to Allah.The Hanafi, Hanbali and most of the Shaafa'i fuqahaa are agreed
    that it is OK for a Muslim to leave something to a dhimmi (non-Muslim living under Islamic
    rule) in his will, and vice versa, so long as this is within the guidelines of
    shareeah. Their evidence for this is the aayah (interpretation of the meaning): Allaah
    does not forbid you to deal justly and kindly with those who fought not against you on
    account of religion and did not drive you out of your homes. Verily, Allaah loves those
    who deal with equity. [al-Mumtahinah 60:8]. Also, being a kaafir does not
    disqualify a person from ownership, and as it is OK to sell to a kaafir or give him a
    gift, it is also OK to include him in ones will.
Some of the Shaafais think that it is OK only if a specific
    person is named, such as saying I leave [such and such] to so and so; but if a
    person says I leave [it] to the Jews and Christians, this is not OK because it
    sounds as if he is making their kufr the reason for leaving something to them. The
    Maalikis agree with others that it is OK for a non-Muslim to leave something to a Muslim.
    With regard to a Muslim leaving something to a non-Muslim, Ibn al-Qaasim and Ashhab said
    that it is allowed if it is done for a reason, such as upholding family ties, otherwise it
    is makrooh, and should not be done at the expense of a Muslim. No one would do such a
    thing except one whose faith is diseased. (al-Mawsooah al-Fiqhiyyah,
    2/312)
    Unfortunately, nowadays we see some Muslims, especially
    those who are living in kaafir countries, leaving huge sums of money to Christian, Jewish
    or other kaafir organizations, on the basis that these are charitable, educational or
    humanitarian organizations and so on, but there is no way that Muslims can benefit from
    this. The only ones who benefit from it are the kuffar, and their hungry oppressed refugee
    Muslim brothers are left with no h elp or support. This is a sign of weak, diluted faith
    and of allegiance to and admiration of the kuffaar and their disbelieving societies. We
    ask Allaah to keep us safe and sound. May Allaah bless our Prophet Muhammad.