Fuṣṣilat

فَإِنْ أَعْرَضُوا فَقُلْ أَنْذَرْتُكُمْ صَاعِقَةً مِثْلَ صَاعِقَةِ عَادٍ وَثَمُودَ

إِذْ جَاءَتْهُمُ الرُّسُلُ مِنْ بَيْنِ أَيْدِيهِمْ وَمِنْ خَلْفِهِمْ أَلَّا تَعْبُدُوا إِلَّا اللَّهَ قَالُوا لَوْ شَاءَ رَبُّنَا لَأَنْزَلَ مَلائِكَةً فَإِنَّا بِمَا أُرْسِلْتُمْ بِهِ كَافِرُونَ

13. But if they turn away, then say: “I have warned you of a destructive awful cry like that which overtook ‘Ad and Thamud.”
14. When the Messengers came to them from before them and behind them [saying]: “Worship none but Allah,” they said: “If our Lord had so willed, He would surely have sent down the angels. So indeed we disbelieve in that with which you have been sent.”

Prophets were divinely appointed to bear glad tidings and warnings unto mankind. These guides are supposed to prognosticate deviations and errors and find solutions to them. It is worthy of note that the blessed Verses in question warn disbelievers and address the Messenger of God (S) that O Muhammad say unto them that if they turn away from Divine Command, you will be cast into perdition through startling torment resembling lightning in the same manner that the peoples of ‘Ad and Thamud were afflicted with destructive gale (sarsar) and awful cry respectively and they were both destroyed.

Verse 14 is saying that the peoples of ‘Ad and Thamud committed sins since they denied the Calls of the divinely appointed Prophets saying that had our Lord willed to send Messengers to us, He would have made angels descend from the heaven, but you are like us and we will never acknowledge your Prophetic mission. They were too ignorant to comprehend that angels are different from mankind by nature and they may neither associate with nor guide them, unless they take the form of human beings; however, in such case they would be regarded as human beings.

The motif is elsewhere attested in the Holy Qur’an¹³: