Praise be to Allaah.
basic principle is that it is permissible for a Muslim to buy what he
needs of that which Allaah has permitted from a Muslim or from a kaafir.
(peace and blessings of Allaah be upon him) bought
from Jews. But when a Muslim chooses not to buy from his Muslim
brother for no reason, i.e., he has not been cheated or deceived, and the
goods are not of poor quality, and he simply prefers to buy from a kaafir
rather than from a Muslim with no justification – this is haraam,
because it weakens the trade of the Muslims and makes them lose sales if
this becomes a habit among the Muslim (consumers). But if he does not buy
from him for a reason such as those mentioned above, then he should advise
his Muslim brother to give up the bad things he is doing. If he accepts
the advice, then praise be to Allaah, otherwise he should leave him alone
and go to someone else, even if he is a kaafir, if he is honest and the
transactions are to the mutual benefit of both parties.