Task: Question Generation
Input (English): Following this battle, Ali fought a battle against Muawiyah, known as the Battle of Siffin. The battle was stopped before either side had achieved victory, and the two parties agreed to arbitrate their dispute. After the battle Amr ibn al-As was appointed by Muawiyah as an arbitrator, and Ali appointed Abu Musa Ashaari. Seven months later, in February 658, the two arbitrators met at Adhruh, about 10 miles north west of Maan in Jordon. Amr ibn al-As convinced Abu Musa Ashaari that both Ali and Muawiyah should step down and a new Caliph be elected. Ali and his supporters were stunned by the decision which had lowered the Caliph to the status of the rebellious Muawiyah I. Ali was therefore outwitted by Muawiyah and Amr. Ali refused to accept the verdict and found himself technically in breach of his pledge to abide by the arbitration. This put Ali in a weak position even amongst his own supporters. The most vociferous opponents in Ali's camp were the very same people who had forced Ali into the ceasefire. They broke away from Ali's force, rallying under the slogan, "arbitration belongs to God alone." This group came to be known as the Kharijites ("those who leave"). In 659 Ali's forces and the Kharijites met in the Battle of Nahrawan. Although Ali won the battle, the constant conflict had begun to affect his standing, and in the following years some Syrians seem to have acclaimed Muawiyah as a rival caliph.
Output (English): Who was appointed arbitrator by Ali?