Al-Walīd ibn Muslim said: Usayd al-Kilābī narrated to us that he heard al-ʿAlāʾ ibn al-Zubayr al-Kilābī relate from his father, who said, “I witnessed Persia conquer Rome, then saw Rome overcome Persia, and later watched the Muslims vanquish both Persia and Rome and establish their rule over Syria and Iraq—all within the span of fifteen years.”