This article explores theological thought of al-Ash‘arî in Abû al-Su‘ûd's work Irshâd al-‘Aql al-Salîm ilâ Mazâyâ al-Kitâb al-Karîm. The study finds an interesting fact that when interpreting the Quranic verses on theological matters, Abû al-Su‘ûd tended to affiliate to Ash‘arîyah. However, Abû al-Su‘ûd firmly stated that he referred most to al-Kashshâf of al-Zamakhsharî in his exegetical works. It has been widely known that al-Zamakhsharî was one of prominent proponents of Mu‘tazilah. The article emphasizes a number of theological issues discussed by Abû al-Su‘ûd in his tafsîr such as God's free will, anthropomorphism, and God's justice. There have been three steps to analyze theological thoughts of Ash‘arîyah mentioned in Abû al-Su‘ûd's work, are: firstly, grouping the most Quranic verses on theological realm referred by mutakallimîn. Secondly, explaining the views of each school (madhhab) of Islamic theology. Thirdly, discussing the assessments and interpretation of Abû al-Su‘ûd on theological verses and comparing them to al-Zamakhsharî's interpretation. Based on these three steps the author will analyze the Ash‘arîyah theological pattern adhered by Abû al-Su‘ûd.