Brief biography of Imaam As-Sijzi
7-11-2017 | IslamWeb
Question:
Shaykh, who was Shaykh Abu Nasr As-Sijzee (d. 444 AH.)? What was his School of Thought and creed?
Answer:
All perfect praise be to Allah, the Lord of the worlds. I testify that there is none worthy of worship except Allah and that Muhammad, sallallaahu ‘alayhi wa sallam, is His slave and Messenger.
Imaam Abu Nasr As-Sijzi 
was one of the leading scholars of Ahlus-Sunnah Wal-Jamaa‘ah and he adhered to the sound Islamic creed held by our righteous predecessors. He composed two famous books in ‘Aqeedah (Islamic Creed): Al-Ibaanah, and Ar-Radd ‘ala Man Ankara Al-Harf was-Sawt.
Al-Haafith Ath-Thahabi said about him:
"The Imaam, scholar, Haafith, well-versed, Shaykh of Ahlus-Sunnah, Abu Nasr ‘Ubaydullah ibn Sa‘eed ibn Haatim ibn Ahmad Al-Waa'ili Al-Bakri As-Sijistaani, Imaam of Al-Haram, the author of Al-Ibaanah Al-Kubra (which advocates that the Quran was not created), which is a big volume that indicates his vast knowledge in this field. He learned four hundred ahaadeeth and studied in Hijaaz, Shaam, Iraq, and Khurasaan... As-Sijzi said in his book Al-Ibaanah, 'Our leading scholars such as Sufyaan, Maalik, the two Hammaads (Hammaad ibn Salamah and Hammaad ibn Zayd), Ibn ‘Uyaynah, Al-Fudhayl, Ibn Al-Mubaarak, Ahmad ibn Hanbal, and Is-haaq, all agreed that Allah, the Exalted, is above the Throne, His knowledge is everywhere, He descends to the lower heaven, He gets angry and is pleased, and speaks of whatever He wishes.' Abu Nasr passed away in Makkah in Muharram, 444 AH." [Siyar A‘laam An-Nubalaa']
Some scholars criticized him regarding his statement that "the speech of the one reciting the Quran is not created." It is a particular matter that does not undermine his status and did not compromise his knowledge in the view of the scholars. For more benefit, please refer to fatwa 243994.
Allah knows best.