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Surah 41. Fussilat
Ayah 13 - 14
13فَإِنْ أَعْرَضُوا۟ فَقُلْ أَنذَرْتُكُمْ صَـٰعِقَةً مِّثْلَ صَـٰعِقَةِ عَادٍ وَثَمُودَ
14إِذْ جَآءَتْهُمُ ٱلرُّسُلُ مِنۢ بَيْنِ أَيْدِيهِمْ وَمِنْ خَلْفِهِمْ أَلَّا تَعْبُدُوٓا۟ إِلَّا ٱللَّهَ ۖ قَالُوا۟ لَوْ شَآءَ رَبُّنَا لَأَنزَلَ مَلَـٰٓئِكَةً فَإِنَّا بِمَآ أُرْسِلْتُم بِهِۦ كَـٰفِرُونَ
[13-14] Now if they turn away,17 say to them, "I warn you of a thunderbolt of punishment the like of which had descended upon the 'Ad and the Thamud. When the Messengers of God came to them from every side, from front and from behind,18 saying, "Worship none but Allah" , they said, "Had our Lord so willed, He would have sent down angels; therefore, we deny what you have been sent with."19
17That is, "If they do not believe that God and Deity is One and only One, who has created this earth and the whole universe, and still persist in their ignorance that they would make others also, who are in fact His creatures and slaves, deities beside Him, and regard them as His associates in His Being and rights and powers.
18This sentence can have several meanings:
(1) That the Messengers continued to come to them one after the other;
(2) that the Messengers tried in every way to make them understand the truth and did not leave any stone unturned to bring them to the Right Path; and
(3) that the Messengers came to them in their own country as well as in the adjoining countries.
19That is "If Allah had disapproved of our religion, and had willed to send a messenger to us to keep us away from it, He would have sent the angels. As you are not an angel but a man like us, we do not believe that you have been sent by God, and sent for the purpose that we give up our religion and adopt the way of life that you are presenting." The disbelievers' saying that they deny "what you have been sent with", was only sarcastic. It does not mean that they believed him to have been sent by God and then denied what he said. But this is a sarcastic expression of the type that Pharaoh had uttered before his courtiers about the Prophet Moses: "This messenger of yowl, who has been sent to you, seems to be utterly mad." (Ash-Shua'ra' 27). For further explanation, see E.N. 11 of Surah Ya Sin.