And verily, the Dwellers of Al-Hijr denied the Messengers. And We gave them Our signs, but they were averse to them.
The Dwellers of the Al Hijr were the people of Thamud who rejected their Prophet, Salih. Whoever denies even one Messenger, then he has disbelieved in all of the Messengers, thus they are described as rejecting "the Messengers."
Allah tells us that he (Salih) brought them signs to prove that what he was telling them was true, such as the she-camel which Allah created for them out of a solid rock in response to the supplication of Salih. This she-camel was grazing on their lands, and the people and the camel took water on alternate days that were well-known. When they rebelled and killed it, he said to them,
تَمَتَّعُواْ فِى دَارِكُمْ ثَلَـثَةَ أَيَّامٍ ذلِكَ وَعْدٌ غَيْرُ مَكْذُوبٍ
"Enjoy yourselves in your homes for three days. This is a promise which will not be belied." (11;65)
Allah said;
وَأَمَّا ثَمُودُ فَهَدَيْنَـهُمْ فَاسْتَحَبُّواْ الْعَمَى عَلَى الْهُدَى
And as for Thamud, We showed them and made the path of truth clear but they preferred blindness to guidance. (41;17)
Allah tells us that,
وَكَانُواْ يَنْحِتُونَ مِنَ الْجِبَالِ بُيُوتًا امِنِينَ