Is the sale of mutual concession (Muwada'ah) permissible?
Chapter on Selling the Musarrah (Animal with milk retained in udder)
Al-Mughni
Book of Sales
Primary text
The sale of Muwada'ah is permissible. This occurs when the seller states their cost price and then says, 'I sell this to you for that price, and I concede to you such and such amount.' If the seller states, 'with a concession of one dirham for every ten,' this is disliked, similar to the ruling on Murabaha, but the sale is valid. The concession is calculated as one dirham deducted from every ten units. Thus, if the cost price was one hundred, the selling price is ninety, and the concession is ten.
Supporting text
A group of scholars held that the concession should be calculated from every eleven dirhams, resulting in a deduction of nine dirhams plus a fraction of a dirham. This view is incorrect because it calculates the deduction from eleven units, contrary to what was stated.