Amir al-mu'minin said to his companions about Mu`awiyah
Soon after me there would be put on you a man with a broad mouth and a big belly. He would swallow whatever he gets and would crave for what he does not get. You should kill him but (I know) you would not kill him. He would command you to abuse me and to renounce me.
As for abusing, you do abuse me because that would mean purification for me and salvation for you. As regards renunciation, you should not renounce me because I have been born on the natural religion (Islam) and was foremost in accepting it as well as in Hijrah ( migrating from Mecca to Medina). (1)
(1). About the person to whom Amir al-mu'minin has alluded in this sermon some people hold that he is Ziyad ibn Abih; some hold that he is al-Hajjaj ibn Yusuf ath-Thaqafi and some hold that he is Mughirah ibn Shu`bah.
But most of the commentators have held him to be Mu`awiyah and this is correct because the qualities that Amir al-mu'minin has described prove true fully on him alone .
Thus Ibn Abi'l-Hadid has written about the gluttonous quality of Mu`awiyah that once the prophet sent for him and he was informed that Mu`awiyah was busy eating. Then a second and third time a man was sent to call him but he brought the same news.
Thereupon the Prophet said , "May Allah never satisfy his belly." The effect of this curse was that when he felt tired of eating he would say , "Take away, for, by Allah I am not satiated but I am tired and disgusted." Similarly, his abusing Amir al-mu'minin and ordering his officers for it are such accepted facts of history about which there is no scope of denying.
In this connection such words were used on the pulpit that even Allah and the Prophet were hit by them. Thus, Umm al-mu'minin Umm Salamah wrote to Mu`awiyah, "Certainly you people abuse Allah and the Prophet, and this is like this that you hurl abuses on `Ali and those who love him, while I do stand witness that Allah and the Prophet did love him." (al-`Iqd al-Farid, Vol. 3, p. 131)
Thanks to `Umar ibn `Abdil-`Aziz who put a stop to it, and introduced the following verse in place of abuse in the sermons:
Verily Allah enjoineth justice and benevolence (to others) and giving unto the kindred, and forbidden lewdness, and evil, and rebellion; He exhorteth you that ye may take heed (Qur'an 16:90)
In this sermon Amir al-mu'minin has ordered his killing on the basis of the Prophet's order that "When you (O' Muslims) see Mu`awiyah on my pulpit, kill him." (Kitab Siffin, pp. 243, 248; Sharh of Ibn Abi'l-Hadid, Vol. 1, p.348; Ta'rikh Baghdad, Vol. 12, p. 181; Mizan al-I`tidal, Vol. 2, p. 128; Tahdhib at-tahdhib, Vol. 2, p. 428; Vol. 5, p. 110; Vol. 7, p. 324)