Surat Ar-Ra`d (7-8)

{وَيَقُولُ الَّذِينَ كَفَرُواْ لَوْلا أُنزِلَ عَلَيْهِ آيَةٌ مِّن رَّبِّهِ إِنَّمَا أَنتَ مُنذِرٌ وَلِكُلِّ قَوْمٍ هَادٍ} (الرعد : 7)

7- And the disbelievers say out of stubbornness: "Why is not a sign sent down to him from his Lord like turning the stick into a snake or reviving the dead?'' The Prophet (peace be upon him) cannot bring these miracles from himself but they are sent to him by Allah according to His Wisdom. Those polytheists ask the Prophet (peace be upon him) to remove the mountains of Makkah and replace them with gardens, and to turn the mountain of Safa into gold.

If Allah had fulfilled their requests and they did not believe, He would have destroyed them all. They only ask them out of stubbornness not for the sake of faith. Allah has supported His Messenger with a permanent miracle which is enough for them i.e., the Glorious Qur'an by which Allah challenged all Arabs to bring ten Surahs of the like but they could not.

O Prophet, you are only a warner who should only convey the message of Allah which He commanded you to deliver and to tell the truth to people and warn them against the bad consequence of those who do not follow you. And to every people there is a guide to the truth, and you are their guide like all previous messengers.

{اللّهُ يَعْلَمُ مَا تَحْمِلُ كُلُّ أُنثَى وَمَا تَغِيضُ الأَرْحَامُ وَمَا تَزْدَادُ وَكُلُّ شَيْءٍ عِندَهُ بِمِقْدَارٍ} (الرعد : 8)

8- The knowledge of Allah encompasses everything, for He knows what every female carries, and all creatures whether humans or animals on the land or in the sea by their different kinds, sizes, colors, and numbers. He also knows what is in wombs where a full fetus or not and the period he is going to stay in the womb, and everything is fixed and estimated by Allah by precise measure and time.