Dought & clear, - Can he sell computer programs even though he is afraid that they may be used for haraam purposes?.

Is it permissible to sell computer programs although I am afraid that
they will use them for sinful purposes and that I may incur a burden
of sin as a result of that, or am I not responsible for what
thepurchaser does after he has bought it from me?
Praise be to Allah.
With regard to programsand computers that may be used for good or bad
purposes, it is permissible to sell them and trade in them, unless it
is known that the purchaser is going touse them for haraam purposes.
In that case it is not permissible to sell them to him. The same
applies if it is thought most likely that he is going to use them for
haraam purposes; it is not permissible to sell them to him in that
case.
But if you are not certainas to whether he will useit for haraam
purposes or not, then there is nothing wrong with youselling it to
him. Then if he uses it for haraam purposes, the burden of sin will be
on him only.
Shaykh al-Islam Ibn Taymiyah (may Allah have mercy on him) said:It is
not valid to sell that which is intended for haraam purposes, such as
juice that will be usedto make wine, if that is known, as is the view
of Ahmad and others, or if it is thought most likely, as is one of the
two opinions of Ahmad. This is supported by the fact that our
companions said: If the landlord thinks it most likely that the renter
is renting the property for sinful purposes, such as selling alcohol
and the like, then it is not permissiblefor him to rent that property
to him, and therental contract is not valid. Sales and rentals are the
same.
End quote from al-Fataawa al-Kubra, 5/388