Ibn Qayyim al-Jawziyya

Shams al-Dīn Abū ʿAbd Allāh Muḥammad ibn Abī Bakr ibn Ayyūb al-Zurʿī l-Dimashqī l-Ḥanbalī (29 January 1292–15 September 1350 CE / 691 AH–751 AH), commonly known as Ibn Qayyim al-Jawziyya ("The son of the principal of [the school of] Jawziyyah") or Ibn al-Qayyim ("Son of the principal"; ابن القيّم) for short, or reverentially as Imam Ibn al-Qayyim in Sunni tradition, was an important medieval Islamic jurisconsult, theologian, and spiritual writer. Belonging to the Hanbali school of orthodox Sunni jurisprudence, of which he is regarded as "one of the most important thinkers," Ibn al-Qayyim was also the foremost disciple and student of Ibn Taymiyyah, with whom he was imprisoned in 1326 for dissenting against established tradition during Ibn Taymiyyah's famous incarceration in the Citadel of Damascus.

Quotes

 * Jihad against the lower self precedes jihad against external enemies and is the basis for it. Indeed, if one does not strive against himself first to do what he has been commanded and avoid what he has been forbidden and to wage war against it for the sake of Allah, one cannot possibly strive against external enemies. How can one strive against his enemies and be just if his enemy within has overpowered him, dominated him, and he did not strive or wage war against it for the sake of Allah? Rather, he cannot go out against his enemies unless he gives precedence to striving against himself.
 * Sins destroy the heart the same way poison destroy the body.
 * Some people remain deprived of knowledge due to their poor ability to remain silent.
 * The one who is truely enslaved is the one who is a slave of his desires.
 * Zād al-maʿād, 3:6. Quoted in "Jihad in Islam: Just-war theory in the Quran and Sunnah", p. 6.