The following is a letter from Imam Ali (a) to Ziyad who was appointed as the Commissioner of Basra by Abdullah bin Abbas, the Governor of the provinces of Ahwaz, Basra, Kirman and Fars. Ziyad was from the very beginning dishonest and corrupt, a man who would not stop short at any vice or sin to gain his end. He had come from a very low family so much so that nobody knew his father's name; his mother was a harlot. Ummul Mu'minin Aisha had nicknamed him as “His father's son” and he was known all over Arabia by this insulting name. But he was a self-made man, a great conspirator. Ibn Abbas had found him a useful officer as he could suppress any voice raised against his government. He appointed him as a commissioner and had recommended him to Imam Ali (a). Imam Ali (a) also gave him a chance and wanted to see whether he could give up his bad ways. But he did not change his behaviour, so Imam Ali (a) dismissed him.
Later on Mu’awiya in his court declared him to be his father's (Abu Sufyaan's) illegitimate son. Ziyad was glad that atleast he could name some big man - though thirty years after the death of that man - to be his father, and thus became a staunch friend of Mu’awiya - his so-called half brother. Imam Ali (a) wrote this letter to Ziyad when he was still the Commissioner of Basra.
I swear by Allah that if I find you misappropriating the wealth of Muslims I will punish you in such a way that you will be left poor. Besides this poverty there will be the burden of sins on your shoulders, you will be disgraced and humiliated, losing your position and prestige.