Umayyad tradition of cursing Ali

Sheites confirm that there was an Umayyad tradition of cursing Ali , that is said to have started with Muawiyah I , a practice put to end by Umar II . this allegation is completely denied by Sunni sects who confirm that Ali Bin Abi Taleb is one of the highly honored companions of the prophet Mohammad ,and cursing him is Blasphemy.But this is prominently mentioned by Shi'a when retelling the history of Islam .It is established from Sunni references that Mu'awiya used to openly curse Ali. Ibn Kathir records in his Al Bidayah wa al Nahayah, "When Mu'awiya went for hajj, he held the hand of Saad bin Abi Waqas and said to him: 'Oh Abi Ishaq! We are the people who abandoned hajj because of wars till we almost forgot some of its laws, so we performed Tawaf (circumambulation) to imitate your Tawaf'. When they completed (hajj), he (Muawiya) entered him (Saad) to a conference room and sat with him on his sofa, then he (Muawiya) mentioned Ali bin Abi Talib and cursed him. He (Saad) said: 'You brought me to your house and made me sit on your sofa and then you begun to curse Ali?'~~ People who chose death over cursing Ali include: Atiyya ibn Sa'd Hujr ibn Adi

The Umayyad tradition of cursing Ali was performed in state-controlled mosques in Syria for a period of approximately 65 years from c.657 to c.717 CE.

Cursing Ali was a state policy pursued by the Umayyad Caliphate between 41 and 132 AH in order to discredit the partisans of Ali and enforce loyalty to the state. The caliphate of Umar II is said to have been an exception, but his reign was short and did not make serious dent in the Umayyad policies. The practice ended eventually only with the overthrow of the Ummayyads.

State policy of the Umayyad Caliphate Cursing Ali was a state policy introduced by Mu'awiya ibn Abi Sufyan , the first Umayyad caliph ( r. 661–680 ), which mandated publicly cursing Ali ibn Abi Talib , the cousin and son-in-law of the Islamic prophet Muhammad , who was also the fourth Rashidun caliph ( r. 656–661 ) and the first Shia Imam . Mu'awiya was the incumbent governor of Syria who had rebelled against Ali ostensibly to avenge the previous caliph Uthman ( r. 644–656 ), who was in turn assassinated by some provincial dissidents angered by his policies. Ali and Mu'awiya fought the inconclusive Battle of Siffin in 657 CE and remained enemies until the assassination of Ali in 661, which paved the way for the caliphate of Mu'awiya in the same year. The public cursing of Ali continued after Mu'awiya and was finally abandoned some sixty years later by the pious Umar II ( r. 717–720 ). The policy likely served as a propaganda measure, and also helped provoke, identify, and then crush the supporters of Ali, whom the Umayyads considered a threat.