Hafidh ad-Dhahabe said in his book “Mizanul itidal” (1/5):
“And extreme person from the sheeah in the time of the early Muslims and according to them was one who spoke ill of and reviled Uthman ibn Affan, Zubayr ibnul Awaam, Talha, Muawiyah ibn Abee Sufyan and a group who fought Alee. Whereas an extreme sheeah in our time and according to us is one who declares them disbelievers and renounces himself from Abu Bakr and also Umar. This one is misguided liar”.
Quoted from “Min aqwal al-munsefeen fi sahabe al-khaliphat Muawiya ibn Abee Sufyan” by Abdulmuhsin Abbad.