Here are a few famous sayings by scholars and historians about Imam Ali (AS), the first Imam of Shia Muslims:

“As for this young Ali, one cannot but like him…. Brave as a lion; yet with a grace, a truth, and affection worthy of a Christian knighthood.”
Thomas Carlyle

“He united the qualifications of a poet, a soldier, and a saint; his wisdom still breathes in a collection of moral and religious sayings.”
Sir Edward Gibbon

“He had contempt of the world, its glory, and pomp; he feared God much, gave much alms, was just in all his actions humble and affable.”
Dr. Henry Stubble

“His talents as an orator and his intrepidity (fearlessness) as a warrior were grateful to a nation in whose judgment courage was virtue and eloquence was wisdom.”
Charles Mills

“His mother was delivered of him at Mecca (in Kaba), in the very Temple itself; which never happened to anyone else.”
Simon Ockley

“He possessed the three qualities most prized by the Arabs: courage, eloquence, and munificence.”
Washington Irving

“With him perished the truest hearted and best Moslem of whom Mohammadan history had preserved the remembrance.”
Robert Durey Osborn

 

Source: shiawisdom.com