grass but then gets separated from it in the morning, as Allah has said, "Set forth to them the similitude of the life of this world: it is like the rain which We send down from the skies: the earth's vegetation absorbs it, But soon it becomes dry stubble, which the winds do scatter: it is (only) Allah Who prevails over all things. Q18:45." He advises his companions to "look at this world and the numerous things which cause you to wonder, and the scarcity of things that benefit you." 60-82 Islamic view of Moses The third main story within the chapter (verses 60–82) is that of Musa (Moses) traveling to gain knowledge from another servant of God who is never mentioned by name, in tafsir of ibn Kathir he is called Al-Khidr. 83-98 Dhul-Qarnayn Finally, the surah mentions in verses 83–98 a man who traveled a great deal and reached the east and the west of the earth – namely, Dhul-Qarnayn. The Qur'an repeats the Syrian legend of a great king who helps a tribe of people build a massive wall of iron between two mountains. It goes on to say that this wall will be only destroyed on Judgement Day. The wall may have reflected a distant knowledge of the Great Wall of China (the 12th-century scholar al-Idrisi drew a map for Roger of Sicily showing the "Land of Gog and Magog" in Mongolia), or of various Sassanid Persian walls built in the Caspian area against the northern barbarians, or a conflation of the two. Circumstances of revelation Arab Muslim historian and hagiographer, Ibn Ishaq, reported in his traditional book (oral traditions) of biography of Muhammad, Sirat Rasul Allah that the 18th surah of the Qur'an (which includes the story of Dhu l-Qarnayn) was revealed to the Islamic prophet Muhammad by God on account of some questions posed by rabbis residing in the city of Medina – the verse was revealed during the Meccan period of Muhammad's life. According to Ibn Ishaq, Muhammad's tribe, the powerful Quraysh, were greatly concerned about their tribesman who had started claiming prophethood and wished to consult rabbis about the matter. The Quraysh sent two men to the rabbis of Medina, reasoning that they had superior knowledge of the scriptures and about the prophets of God. The two Quraysh men described their tribesman, Muhammad, to the rabbis. The rabbis told the men to