Quote:The question of Ali's right to succeed to the caliphate is an article of faith which divided the Muslim world into two great sects, the Sunni and the Shi'a. The Sunnis believe that the prophet chose Abu Bakr to be the first caliph, while the Shia believe that he chose Ali and announced it in public in Ghadir Khum. Whatever the case, Ali did not challenge Abu Bakr or any of the later caliphs, rather he served as an advisor to them.
Ali is greatly respected by all Muslims, both Sunni and Shi'a. The Shi'a in particular venerate him as second only to the prophet. They also celebrate the anniversaries of his martyrdom and birth; the Shia version of the adhan also includes an explicit reference to Ali. Ali is described as a bold, noble and generous man, "the last and worthiest of the primitive Muslims, who imbibed his religious enthusiasm from companionship with the prophet himself, and who followed to the last the simplicity of his example."
In the eyes of the later Muslims he was remarkable for learning and wisdom, and there are extant collections of proverbs and verses which bear his name: the Sentences of Ali. The most famous collection of Ali's speeches and letters is the Nahj al Balagha meaning "The peak of eloquence."
Source/Article: http://www.wordiq.com/definition/Ali_ibn_Abi_Talib
