Al-Ash'ari composes Maqalat al-Islamiyyin and his refutations of the Mu'tazila

After his repentance al-Ash'ari set about refuting the Mu'tazila, and composed the many works he himself lists in al-Umd fi'l-Ru'ya, among them al-Fusul fi'l-Radd ala'l-Mulhidin in twelve books, Khalq al-A'mal, al-Sifat, al-Ru'ya bi'l-Absar, Idah al-Burhan, al-Luma' fi'l-Radd ala Ahl al-Bida', al-Naqd ala'l-Jubba'i, and a tafsir ¹; Ibn al-Nadim names al-Luma', al-Mujaz, al-Tabyin an Usul al-Din and al-Sharh wa'l-Tafsil fi'l-Radd ala Ahl al-Ifk wa'l-Tadlil ².

Most famous is his Maqalat al-Islamiyyin wa-Ikhtilaf al-Musallin, the descriptive work presenting the doctrines of the sects which displays his intimate knowledge of Mu'tazilite views ³; in it he sets out the position of the hadith scholars and Ahl al-Sunna and says he holds it, and the edition of the book describes him as the shaykh of Ahl al-Sunna wa'l-Jama'a ⁴.