Ruling on printing books of the salaf or contemporary scholars and selling them – is it essential to have permission?

Firstly: 

Copyright is one of the
intangible rights that are protected by sharee’ah, as has been explained in
the answer to question no. 26307. 

Secondly: 

There is nothing wrong with
printing and selling religious books, because the basic principle is that it
is permissible, and because it is a means of spreading knowledge, improving
its quality and making it available to people, which cannot be done except
by dealing in books.

Based on that, there is
nothing wrong with printing any of the books of the salaf or contemporary
scholars, unless their authors have not permitted it, in which case it is
essential to have their permission, as well as to be trustworthy and honest
in publishing these books. That also includes things that a scholar wrote
without the aim of making money. It is permissible to print it and sell it
and make money from it, so long as he did not object to that, in which case
it is essential to have permission from him or his heirs.  

It says in Fataawa
al-Lajnah al-Daa’imah (13/187): 

Question: Is it permissible
to record a tape and sell it, but without asking permission from the author
or, if the author is no longer alive, from the publisher, to record it? Is
it permissible to make many copies of a book and sell them? Is it
permissible to make a copy of a book and not sell it, rather keep it for
myself? If the book carries the mark “All rights reserved”, should I ask for
permission or not? Please advise me, may Allaah bless you.

Answer: There is nothing
wrong with recording useful tapes and selling them, or copying books and
selling them, because that is helping to spread knowledge, unless the
authors have not allowed that, in which case it is essential to have their
permission. End quote. 

And Allaah knows best.