يعد كتاب "البيان والتبيين" من أكثر كتب الجاحظ تداولاً، وأعظمها نفعًا، قال فيه ابن خلدون: «سمعنا من شيوخنا في مجالس التعليم أن أصول فن الأدب وأركانه أربعة دواوين، وهي: أدب الكاتب لابن قتيبة، وكتاب الكامل للمُبَرِّد، وكتاب البيان والتبيين للجاحظ، وكتاب النوادر لأبي علي القالي، وما سوى هذه الأربعة فتبع لها وفروع عنها». ويصف أبو هلال العسكري البيان والتبيين بأنه "كثير الفوائد، جم المنافع، لما اشتمل عليه من الفصول الشريفة، والفقر اللطيفة، والخطب الرائعة، والأخبار البارعة، وما حواه من أسماء الخطباء والبلغاء، وما نبه من مقاديرهم في البلاغة والخطابة وغير ذلك من فنونه المختارة، ونعوته المستحسنة. إلا أن الإبانة عن حدود البلاغة وأقسام البيان والفصاحة مبثوثة في تضاعيفهš
Because of the caliphs' patronage and his eagerness to establish himself and reach a wider audience, al-Jāḥiẓ stayed in Baghdad (and later Samarra), where he wrote a huge number of his books. The caliph al-Ma'mun wanted al-Jāḥiẓ to teach his children, but then changed his mind when his children were frightened by al-Jāḥiẓ's goggle-eyes. This is said to be the origin of his nickname.
He enjoyed the patronage of al-Fath ibn Khaqan, the bibliophile boon companion of Caliph al-Mutawakkil, but after his murder in December 861 he left Samarra for his native Basra. He died there in late 868, according to one story, when a pile of books from his private library collapsed on him.
Most important books: *Kitab al-Hayawan (Book of the Animals) *Kitab al-Bukhala (Book of Misers) also (Avarice & the Avaricious) *Kitab al-Bayan wa al-Tabyin (The Book of eloquence and demonstration) *Risalat mufakharat al-sudan 'ala al-bidan (Treatise on Blacks)
Al-Jāḥiẓ returned to Basra with hemiplegia after spending more than fifty years in Baghdad. He died in Basra in the Arabic month of Muharram in AH 255/December 868-January 869 CE. His exact cause of death is not clear, but a popular assumption is that Jahiz died in his private library after one of many large piles of books fell on him, killing him instantly.