al-Qamar

وَنَبِّئْهُمْ أنَّ الْمَاء قِسْمَةٌ بَيْنَهُمْ كُلُّ شِرْبٍ مُّحْتَضَرٌ

28. And We inform them that the water is to be shared between them and the she-camel, each one of them receive the allotted share.

Addressed to Prophet Salih (as), the blessed Verse in question is asking him to inform the people of Thamud that they should divide the water between themselves and the she-camel. There was seemingly a fountain whose water sufficed to provide the people inhabiting the region with water. The people of Thamud were assigned to make use of the water one day and leave it to the she-camel the next day and receive milk from her in return. However, they rejected the offer and suffered the evil consequences of their deeds and it will be reflected in the following Verses.