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

                What is the ruling on printing and selling Islamic books and making a profit from this? Like the books of the scholars of the Salaf (early generations) and also the books of the recent scholars who write these books so that people benefit from them and not for profit. Is making profit from these books not my right? I have read the answers regarding the intellectual property rights, but I need more explanation.
Praise be to Allah.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.