The Story of Thamud Allah states here that,كَذَّبَتْ ثَمُودُ بِالنُّذُرِThamud denied the warnings.i.e. the people of Thamud denied their Messenger Salih,فَقَالُوا أَبَشَرًا مِّنَّا وَاحِدًا نَّتَّبِعُهُ إِنَّا إِذًا لَّفِي ضَلَلٍ وَسُعُرٍ