 Complete the following phrase:  According to Abu Yusuf Absha al-Qadi, Caliph al-Mamun of Baghdad in 830 CE stood with his army at the gates of Harran and questioned the Harranians about what protected religion they belonged to. As they were neither Muslim, Christian, Jewish or Magian, the caliph told them they were non-believers. He said they would have to become Muslims, or adherents of one of the other religions recognized by the Quran by the time he returned from his 