Abū al-Qāsim al-Qushayrī al-Naysābūrī, born in 986 CE, was a prominent Arab Muslim scholar and theologian from Nishapur, a significant center of Islamic civilization. He mastered numerous Islamic sciences, including jurisprudence, Hadith narration, and Quranic commentary, while also embracing mysticism and an ascetic lifestyle. Al-Qushayri received a traditional education before dedicating himself to Sufism under the guidance of Shaykh Abū ʿAlī al-Daqqāq, whose daughter he later married. He succeeded his master, leading mystical assemblies and establishing a renowned school in Nishapur. His travels included a pilgrimage and journeys to Baghdad, where he taught Hadith and gained recognition at the Caliph's palace. Despite facing political unrest, he eventually returned to Nishapur and remained there until his death in 1072 CE.

Al-Qushayri is highly regarded for his profound contributions to Sufi thought. His seminal work, 'Laṭā'if al-Isharat bi-Tafsīr al-Qur'an,' offers a comprehensive commentary on the Quran, proposing four distinct levels of meaning. The first, 'ibara,' is the literal meaning accessible to all believers. The second, 'ishara,' is accessible to the spiritual elite, extending beyond the text's apparent sense. 'Laṭā'if' refers to subtleties intended for saints, while 'ḥaqā’iq' represents ultimate truths comprehensible only to prophets. This layered approach to scriptural understanding solidified his position among elite Sufi mystics and established his work as a benchmark for Sufi philosophy.

His fame is largely attributed to 'al-Risala al-Qushayriyya' (The Epistle on Sufism). This influential text served a dual purpose: to remind his contemporaries of the authentic lineage of Sufi traditions and to defend Sufism against contemporary criticisms. Al-Qushayri emphasized his deep respect for his Sufi masters, particularly Abū ʿAlī al-Daqqāq and al-Sulami, whose teachings heavily influenced his work. The epistle meticulously outlines the creed of Sufis, profiles significant historical Sufi figures, and clarifies fundamental Sufi terminology with his own interpretations. It also details specific Sufi practices and techniques, making it an essential guide for later Sufi practitioners and scholars, evidenced by its numerous translations.

Beyond his mystical pursuits, Al-Qushayri was a distinguished scholar in various Islamic sciences. He was a jurist, legal theorist, Quranic commentator, Hadith scholar (muhaddith), grammarian, and orator. His grandson, Abd al-Ghafir al-Farsi, described him as 'the absolute Imam, jurist, theologian... the axis of reality, source of happiness, the pole of masterhood, one who joined the Shari'a and the Truth.' Contemporaries lauded his vast knowledge, logical acumen, and profound spiritual influence, noting that his teachings were considered a precursor to the work of Imam al-Ghazali, particularly 'al-Risala al-Qushayriyya' serving as a blueprint for 'Ihya 'Ulum al-Din'.

““Al-Jurayri saw al-Junayd in a dream [after his death] and asked him: ‘How are you, Abu al-Qasim?’ He answered: ‘Gone are all those allegorical allusions (isharat), and all those unequivocal expressions ('ibarat) have vanished. Only those praises of God that we used to utter in the morning have benefited us [in the Hereafter]!’ ””