When Muawiya Ibn Abi Sufyan put al-Mughairah Ibn Shu'ba in charge of Kufah in Jumada 41 (September 2- October 30, 661), he summoned him. After praising and glorifying God, he said:
"Now then, indeed a forbearing person has been admonished in the past... The wise might do what you want without instruction. Although I have wanted to advise you about many things, I left them alone, trusting in your discernment of what pleases me, what helps my regime and what sets my subjects [raiyyah] on the right path. I would continue to advise you about a quality of yours- do not refrain from abusing Ali and criticizing him, not from asking God's mercy upon Uthman and His forgiveness for him. Continue to shame the companions of Ali, keep at a distance, and don't listen to them. Praise the faction of Uthman, bring them near, and listen to them.
Ref: History of Tabari, English version, events of year 51 AH, Execution of Hujr Ibn Adi, volume 18, pages 122-123.
Imam Ibn Jareer Tabari records: The Messenger of Muawiya then came to them with orders to release six and to kill eight, telling them:
We have been ordered to let you disavow Ali and curse him. If you do so, we shall release you, and if you refuse, we shall kill you.
Ref: History of Tabari, English version, events of year 51 AH, volume 18, page 149.
Imam Ibn Jarir Tabari also records:
"Al Hasan had already made peace with Muawiya on condition that he concede to him what was in his treasury plus the revenue (kharaij) of Darabjird and that Ali is not reviled in his hearing."
Ref: History of Tabari, volume 18, page 5.
We read the following account in the History of Tabari:
"When Busr spoke on the pulpit (minbar) of al Basrah, he reviled 'Ali. Then he said 'I imlore God, that anyone knows that I am truthful should say so, or likewise if I am a liar" When Abu Bakrah said, "By God we know you only as a liar "(Busr) order him to be strangled"
Ref: History of Tabari, volume 18 (English version), page 15.
On the authority of Abu Sa’id al-Khudri, who said: The Prophet (s) said: “By the One who possesses my soul, no man will bear enmity towards us, the Ahl al-Bayt, except that Allah will make him enter the Fire (of hell).”
Its chain of narration (isnad) is Sahih according to the author Ibn Hibban, and is Hasan (good), according to the editor Shu’ayb al-Arna’ut.
Ref: Sahih-Ibn-Hibban, page 435.