Is the tile manufacturer entitled to demand a price increase on the previously agreed-upon price, based on the rise in material costs, or must he adhere to the original price?

The transaction mentioned has two possibilities:

1. The buyer purchased a known quantity of tiles, paid part of the price, and the seller took possession of them and left them with him. This is a valid sale, and the seller has no right to retract it.

2. The contract was for tiles described but not yet specified, to be manufactured by the factory. This is a manufacturing contract (Istisna'), and it is permissible to defer the price or part of it. It is not permissible to retract the specification because it is a binding contract according to the Islamic Fiqh Academy, while some held it to be non-binding.

If the price of the tiles increased due to unforeseen circumstances that led to a significant and oppressive increase in manufacturing costs for the seller, the judge has the right to adjust the matter to remove the harm from the affected party.