Al-Aref attended the Nebi Musa religious festival in Jerusalem in 1920 riding on his horse, and gave a speech at the Jaffa Gate. The nature of his speech is disputed. According to Benny Morris, he said "If we don't use force against the Zionists and against the Jews, we will never be rid of them", while Bernard Wasserstein wrote "he seems to have co-operated with the police, and there is no evidence that he actively instigated violence". In fact, "Zionist intelligence reports of this period are unanimous in stressing that he spoke repeatedly against violence". Soon the festival became a riot involving attacks on the local Jews. Al-Aref was arrested for incitement, but when he was let out on bail he escaped to Syria together with co-accused Haj Amin al-Husseini. In another version, he was warned and escaped before being arrested. He advised Arabs against violence, urging them instead to adopt the "discipline, silence, and courage" of their opponents. In his absence, a military court sentenced him to 10 years imprisonment.