Al-Nahw al-Wafi by Abbas Hasan is a monumental four-volume encyclopedia on Arabic grammar, published by Dar al-Ma'arif. Widely regarded as one of the most comprehensive and authoritative modern references on the subject, this work is indispensable for advanced students, researchers, and specialists. Hasan provides exhaustive explanations, rich examples from the Quran and classical literature, and addresses complex grammatical points with exceptional clarity, making it a cornerstone of any serious Arabic linguistics library.