Abūʾl-Ḥusayn Hilāl b. Muḥassin b. Ibrāhīm al-Ṣābīʾ (Arabic: ابو الحسين هلال بن محسن بن ابراهيم الصابئ) (born: 358 A.H./c. 969 A.D., died: 447-448 A.H./1056 A.D.) (aged 90 lunar) was a historian, bureaucrat, and writer of Arabic. Born into a family of Sabian bureaucrats, al-Ṣābi converted to Islam in 402-403 A.H/1012 AD.^[1] First working under the Buyid amir Ṣamṣām al-Dawla, he later became the Director of the Chancery^[1] under Baha' al-Daula's vizier Fakhr al-Mulk.

Hilal al-Sabi' is the author of numerous books, not all of which have survived. Bureaucratic matters and matters of the court were his main themes, along with history.

• The Rules and Regulations of the Abbasid Court - (Arabic: رسوم دار الخلافة Rusum dar al-khilafa)

Perhaps his most famous book is the Rusum dar al-khilafa which is a manual for behavior and work in the Abbasid court of late Buyid Baghdad. Though it is designed as a set of instructions and advice, the book contains numerous statistics, anecdotes and historical asides.

• The Book of Viziers - (Arabic: كتاب الوزراء Kitab al-wuzara)

Only of the beginning of this work has survived, which deals with the viziers of the caliph Al-Muqtadir.

• History of Hilal al-Sabi' - (Arabic: تاريخ ابي الحسين هلال بن المحسن بن ابراهيم الصابي Tarikh Hilal al-Sabi)

This too survives only in fragmentary form, but its fragments fill a gap in the chronicles of the late Buyid era, up to the year 393 hijri (1003 AD).

• Category:Sabian scholars from the Abbasid Caliphate
• Al-Battani
• Thābit ibn Qurra

• Sourdel, D. (1971). "Hilāl b. al-Muḥassin b. Ibrāhīm al-Ṣābiʾ". In Lewis, B.; Ménage, V. L.; Pellat, Ch. & Schacht, J. (eds.). The Encyclopaedia of Islam, Second Edition. Volume III: H–Iram. Leiden: E. J. Brill. OCLC 495469525.
• Hilāl al-Sābi’. Rusūm Dār al-Khilāfa: The Rules and Regulations of the Abbasid Court. Trans. Elie A. Salem. American University of Beirut, 1977.

• List of Muslim historians
• Islamic scholars