Imam as-Sa’di (rahimahullaah) was well educated and had a broad intellect that no one at his time could reach. In addition, he based much of his learning upon the teachings of Shaykh al-Islam ibn Taymiyyah and ibn al-Qayyim; they were also known for their comprehensive and vast knowledge. Shaykh al-Islam ibn Taymiyyah was not someone strictly rigid in his thoughts and so forth; he had ijtihaadat and conclusions that sometimes even opposed the opinions of the four imams. Shaykh as-Sa’di was greatly affected by the way of ibn Taymiyyah. He also used to read a great deal, including magazines from India, Egypt and Greater Syria. Shaykh Muhammad ibn Saalih al-'Uthaimeen (rahimahullaah) even mentioned to our Shaykh, Sami as-Sghair (hafidhahullaah) that Imam as-Sa’di told him that during his time, they were thinking about reconciling the vibrations in the air so they could come to know the words of people that travel through the air and to try to figure out these sounds; currently, they are still doing extensive research into this, and Shaykh as-Sa’di spoke about this over sixty years ago. Moreover, he was one of the first to speak about the issue of organ transplants, and he considered it to be permissible then. All of those who write about organ transplants in our time refer to his name as one great reference in this respect. Furthermore, the Shaykh was known for writing, advising and even correcting things in certain publications. He used to write the magazine, al-Manaar that was published years ago by the scholars of Egypt, including Shaykh Muhammad Rashid Ridah (rahimahullaah).
With a thorough and vast knowledge of the technological progress of his time, the Shaykh (rahimahullaah) notes that this foundation, regarding that which is purely beneficial/harmful and predominantly good/evil, applies to all the contemporary discoveries and innovations that are beneficial to people in their lives and in their deen; they are from the matters which Allaah and His Messenger commanded and are beloved to them and are part of the favors of Allaah on His slaves. The Shaykh (rahimahullaah) mentions the examples of the cables for communication and industry; he says this foundation is applicable to them as well. Some advancements may fall under that which is obligated, others recommended, and others allowable.
Similarly, in our times, these invented matters of instruments and so forth are classified into three categories. Some are used only in good, and the ruling on them is clear; some are used purely in evil, and the ruling on them is also clear. Some are used for both good and evil. In origin, this third type is allowable; however, whoever uses it in evil, for them it is haram, and for those who use it for good, it is halal.
Examples of this include radios, recordings, computers, networks, and even the knife; the knife can be used in goodness like sacrificinh to Allaah, and the knife can also be used in evil to harm people. However, if most people use any instrument to do evil, then we prevent it and say it is not allowed.
The first foundation in Imam ‘Abd ar-Rahman ibn Naasir as-Sa’di’s book, al-Qawaa'id wal-Usool al-Jaami'ah wal-Furooq wat-aqaaseem al-Badee'ah an-Naafi'ah (The Basic Rulings and Principles of Fiqh – The Beneficial, Eloquent Classifications and Differentiations), is entitled: The Lawgiver orders only that which is a purely beneficial (i.e. no evil therein) or predominately beneficial (meaning its benefits exceeds any evil therein). The Lawgiver forbids only that which is purely evil or predominately evil (i.e. the good is negligible when compared to the evil), giving precedence to warding off the evil.
All Praise is due to Allaah, and may the salaah and salaam be on Prophet Muhammad, his household, the noble companions and those who follow them until the Day of Resurrection.