(Al-Fajr) 89 : 9
وَثَمُودَ الَّذِينَ جَابُوا الصَّخْرَ بِالْوَادِ
And Thamud, who made constructions in the valley by carving the rocks.
The people of Messenger Swalih are Thamud. They were making houses and halls by carving the rocks. See explanation 26: 149 and 41: 17.