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Surah 7. Al-A'raf
Ayah 184 - 186
184 أَوَلَمْ يَتَفَكَّرُوا۟ ۗ مَا بِصَاحِبِهِم مِّن جِنَّةٍ ۚ إِنْ هُوَ إِلَّا نَذِيرٌ مُّبِينٌ
185 أَوَلَمْ يَنظُرُوا۟ فِى مَلَكُوتِ ٱلسَّمَـٰوَٰتِ وَٱلْأَرْضِ وَمَا خَلَقَ ٱللَّهُ مِن شَىْءٍ وَأَنْ عَسَىٰٓ أَن يَكُونَ قَدِ ٱقْتَرَبَ أَجَلُهُمْ ۖ فَبِأَىِّ حَدِيثٍۭ بَعْدَهُۥ يُؤْمِنُونَ
186 مَن يُضْلِلِ ٱللَّهُ فَلَا هَادِىَ لَهُۥ ۚ وَيَذَرُهُمْ فِى طُغْيَـٰنِهِمْ يَعْمَهُونَ
[184-186] And have they never reflected on this matter? There is no tinge of unsoundness of mind in their companion; he is a Warner, who is warning plainly (beforehand of the evil consequence). Have they never considered the functioning of the heavens and the earth, and have they never observed closely anything that Allah has created?143 And has it never occurred to them that their life might have come near to its end?144 Then what else can there be in which they will believe after this warning of the Messenger? Whomever Allah deprives of guidance has no guide, for Allah leaves such people wandering about blindly in their contumacy.
143These questions have been posed to refute the charge that their comrade, Muhammad (Allah's peace be upon him), was suffering from a disorder of the mind, for otherwise he would not have given the Message he was conveying. They have been asked to reflect upon the fact that he was born and bred among them and had been their comrade before he claimed that he was appointed a Messenger by Allah. During all those years they had known him to be of a sound mind and of a good nature. Thus it is obvious that they charged him of having a distracted mind not because of what he said before his Prophethood but because of what he proclaimed as a Prophet. That is why they have been asked to reflect upon and point out anything from his Message which they regarded as meaningless, unreal and irrational. If they had ever reflected upon the wisdom of the wonderful administration of the heavens and the earth or observed closely any creation of Allah, they would have come to the inevitable conclusion that the whole system of the universe, nay, each and every particle of His creation is a clear evidence of the Truth of His Message. For all these things refute shirk and prove the Oneness of Allah and invite people to His worship and arouse in them the sense of responsibility and accountability. And that was what their brother was preaching.
144That is to say, "They do not realize even this much that none knows the exact time of one's death, and that they should, therefore, make the best use of the respite that has been given them and repent and reform themselves; otherwise they will meet with serious consequences."