(And they swear a solemn oath by Allah that if there come unto them a portent they will believe therein...) [6:109] up to (Howbeit, most of them are ignorant) [6:111].
Muhammad ibn Musa ibn al-Fadl informed us> Muhammad ibn Ya‘qub al-Umawi> Ahmad ‘Abd al-Jabbar> Yunus ibn Bukayr> Abu Ma‘shar> Muhammad ibn Ka‘b who said: “The Quraysh spoke to the Messenger of Allah, Allah bless him and give him peace. They said: ‘You inform us that Moses, peace be upon him, had a staff with which he struck a stone and twelve springs gushed forth, and that Jesus, peace be upon him, revived the dead, and that Thamud had a camel; why do you not bring us some of those signs so that we believe in you?’ The Messenger of Allah, Allah bless him and give him peace, asked them: ‘What sign do you want me to bring you?’ They said: ‘Turn [mount] al-Safa into gold’. He said: ‘Would you believe in me if I did as you ask?’ They said: ‘Yes, by Allah, if you do, we will all follow you’. The Messenger of Allah, Allah bless him and give him peace, stood up and began supplicating. Then, Gabriel, peace be upon him, came to him and said: ‘If you wish, I can turn al-Safa into gold. However, never did I send a sign that people disbelieved in except that I sent chastisement after it. If you wish, I will leave them until some of them decide to repent’. The Messenger of Allah, Allah bless him and give him peace, said: ‘Leave them until some of them decide to repent’. And so Allah, exalted is He, revealed (And they swear a solemn oath by Allah that if there come unto them a portent they will believe therein) up to His words (… they would not believe unless Allah so willed…) [6:111]”.
Asbab Al-Nuzul by Al-Wahidi , trans. Mokrane Guezzou