lacked any evidence. He also challenged Mu'awiya to name any Syrian who would qualify to vote in a . As for handing Uthman's killers to Mu'awiya, Ali asked the latter to pledge allegiance and then present his case before Ali's court. Ali viewed this as a rebellion against the legitimate Muslim caliph, that is, a challenge to "God's authority." Mu'awiya's motives Modern authors often suggest that Mu'awiya defied Ali after he deposed him as the governor of Syria, or conditioned his pledge to Ali on the revenge for Uthman, knowing that Ali would dismiss him after giving his oath. At the time, Mu'awiya was repeatedly accused of abandoning Uthman during the deadly siege of his residence, and Ayoub thus views Mu'awiya's claim of revenge as a pretext. Other modern authors also tend to consider Mu'awiya's call for revenge as a guise, intended initially to maintain his rule over Syria, or to seize the caliphate altogether later. For McHugo, this view is corroborated by Mu'awiya's secret offer to recognize the caliphate of Ali in return for Syria and Egypt. An exception is Kennedy, who believes that Mu'awiya was sincerely seeking justice for Uthman. Some authors instead regard the call for revenge as a pious cloak for broader issues: Hinds and Poonawala trace back Mu'awiya's revolt to his demands to rule over an autonomous Syria, which was kept free (unlike Iraq) from uncontrolled immigration to check the Byzantine threats. In contrast, after the Byzantines' defeats, Ali might have expected all provinces to equally share the burden of immigration. Shaban has a similar view. Verse 17:33 of the Quran was cited by Mu'awiya to justify revenge, "If anyone is killed wrongfully, We give his next-of-kin authority, but let him not be extravagant in killing, surely he is being helped," although Madelung suggests that the clause about a commensurate response was later ignored in the "frenzy of patriotic self-righteousness" created by Mu'awiya. Mu'awiya's other justification for revolting against Ali was that he had not participated in the election of Ali, or that the rebels were involved in the election. Regarding the emphasis on a Syrian after Ali, Mu'awiya's justification was that the people of Hejaz had abandoned the truth and it was now the Syrians who had to uphold the justice, as explained in a letter attributed to him shortly before the Battle of Siffin. In reality, however, this emphasis was likely to ensure