Al-ʿAbbās ibn Saʿid al-Jawharī;
(c. 800 Baghdad? – c. 860 Baghdad?) was a geometer who worked at the House of Wisdom in Baghdad and for in a short time in Damascus where he made astronomical observations. He was probably of Iranian origin. His most important work was his Commentary on Euclid’s Elements which contained nearly 50 additional propositions and an attempted proof of the parallel postulate.