William Muir,
The Caliphate: Its Rise, Decline and Fall…
“ By the faithful discharge of important trusts, Ziyad overcame the disadvantage of servile birth, rose to important office, and eventually was appointed by 'Ali to the government of Al-Basra and Istakhr. Powerful, wise, and eloquent, he was by far the ablest statesman of the day. Devoted to the cause of 'Ali, he was bitterly opposed to the pretensions of Mu'awiya, even after the abdication of Al-Hasan. ”
