With the advice of Sheikh Dekkâk, he was engaged in the study of external sciences and reached an important level in science branches such as fiqh and kalam. After the death of his mentor, Abu Ali Dekkâk, Kuşeyrî joined the famous sufi and muhaddis Abu Abdurrahman-ı Sülemi and continued to receive his mystical education and hadith science from him. With the death of Sülemî, Kuşeyrî accelerated his writing of works, establishing private conversation and knowledge circles, and carrying out his activities of guidance and science. In fact, there was a circle of lessons allocated to him during the time of his first master, Abu Ali Dekkāk. At the end of a fruitful life, he attained God’s mercy on 16 Rabi-ul-Awwal 465 (30 December 1072).
Imam Qusayri, who is also the leader of a sect attributed to him, is a sufi and mentor who has had significant influences in the history of Sufism with his knowledge, works and views.
Some of his works: Er-Risâletü’l-Kuseyriyye fi’t-Sufi; Letâifü’l-İşârât; et-Tefsírű’l-Kebîr (et-Teysîr fi İlmi’t-Tafsîr); et-Tahbîr fi’t-Tazkîr; Tertibü’s-Sülük fi Tarîkıllâh; Complaint of the Ahl as-Sunna; al-Fusûl fi’l-Usul; Kitâbü’l-Miʻrâc; Nahvü’l-Kulub; Kitâbu Tevhid’n-Nabawi; al-Kasidetu’s-Súfiyya.