The idolaters demanded miracles like those of Jesus Christ:
[Quraish tribesmen said to the Prophet – salam to him: "If you truly are a Prophet as do you claim, then do for us the miracles that Jesus son of Mary did before, and then we may believe you; because Jesus cured the congenitally blind and the albino; he also revived the dead and foretold about the 'Unknown'."
Therefore, this aya was revealed in reply to their words:]
Quran 6: 50, which means:
(
Say [Mohammed, to these disbelievers]:
"I am not telling you that I have the treasuries of [the mercy of] God [so that I can work miracles like those of Jesus who cured the congenitally-blind and the albino and revived the dead],
nor that I know the Unknown,
nor that I am angel [like him, because Jesus was an angel that came down from heaven according to God's command, and entered in the body of the fetus in the womb of Mary.]
I only follow [the commands] revealed to me [from my Lord.]"
Say: "Are the blind [to the way of the truth like Abu-Jah'l], and the man seeing [it like Mohammed] equal?
Will you not contemplate [about that?]")
More explanation is in the link:
http://quran-ayat.com/pret/6.htm#a6_50
quran-ayat.com/pret/6.htm#a6_50
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Further explanation of the previous aya:
So God gave to Jesus Christ those miracles in order that they might respect him, and might not kill him.
But in spite of that, such miracles did not avail anything with the Children of Israel; because
when the Jews saw such miracles which Moses had not brought before, they denied them and said: “These are not the miracles of prophets, but they are only a great sorcery done by a devil having much knowledge about the sorcery.”
While
when the Christians saw such miracles which he worked, they became enthusiastic about him, until they ascribed him as the son of God, and another sect claimed he is God Himself.
Therefore, the material miracles are useless, because they will lead to destruction and to admission into the Fire; so when you see the miracles which you demand, done as you demanded:
>> either you will deny them and say: 'This is an obvious sorcery!'
as did Jews claim about the miracles of Jesus;
>> or you will be enthusiastic about me and say he is the son of God
as did Christians say, and then your destination [in both cases] will be in the Fire.
So the material or objective miracles will not avail anything to let you believe; but
better than this, you should think with your minds and look with your eyes to these stones which you worship: Can they profit or harm you? And in case you realize that they cannot do anything of that, then abandon them, and instead worship God your Lord and Creator and your Provider with the provision, if you believe in my words.
http://quran-ayat.com/pret/6.htm#a6_50
quran-ayat.com/pret/6.htm#a6_50