Surah Al-Isra' (The Night Journey), Verse 59

وَمَا مَنَعَنَاۤ اَنْ نُّرْسِلَ بِالْاٰیٰتِ اِلَّاۤ اَنْ كَذَّبَ بِهَا الْاَوَّلُوْنَ وَاٰتَیْنَا ثَمُوْدَ النَّاقَةَ مُبْصِرَةً فَظَلَمُوْا بِهَا وَمَا نُرْسِلُ بِالْاٰیٰتِ اِلَّا تَخْوِیْفًا ۟

Wa maa mana'anaaa an nursila bil aayaati illaaa an kazzaba bihal awwaloon; wa aatainaa Samoodan naaqata mubsiratan fazalamoo bihaa; wa maa nursilu bil aayaati illaa takhweefaa

“And We refrain from sending the signs, only because the men of former generations treated them as false: We sent the she-camel to the Thamud to open their eyes, but they treated her wrongfully: We only send the Signs by way of terror (and warning from evil).”

Quran 17:59 (Yusuf Ali Translation)