Selling the water of a pond

Question

Here almost everyone has ponds, and near these ponds there are also lands. Water is needed to cultivate these lands. The landowner buys from the owner of the pond all the water that is present in the pond. Is this permissible or not? Is it not a sale of something unknown (majhul)?

Answer

If the pond was made by digging a pit, and the water was kept in it, guarded and looked after, then the sale of whatever quantity of water is present in the pond before one’s eyes is valid, even if its quantity is not known: when the thing pointed to is before one’s eyes, it is not necessary to know its quantity — provided that the whole of it is sold in a single transaction…

Source: Fatawa Mahmudiyya

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