because a ruling revolves around its effective cause: whatever meets the condition for validity is valid, while whatever does not meet the condition for validity is not valid.

Another example: he gives him one dinar to exchange for ten dirhams, but he finds only five dirhams. Is the transaction valid?

We say: the contract is valid with respect to what has been received, and invalid with respect to what has not been received. Thus, the contract is valid for half of the dinar, while the other half remains as a trust with the seller. This dinar is therefore jointly owned by the seller and the buyer.

The benefit of this is that if the price of gold rises between this transaction and the time he receives what is due to him, when the other party finds the remaining dirhams, then any change in price is borne by its owner. For example, if, when the dinar was exchanged for dirhams, one dinar was worth ten dirhams, and it later became worth twenty dirhams, then the remaining half dinar is worth ten dirhams, because the portion of the dinar that remained with the other party was left with him as a deposit, and the contract concerning it was not valid.

If he does not hand over anything at all, the contract is invalid in its entirety. A comparable case is when a person buys jewelry from someone for ten thousand riyals and pays him only five thousand riyals, saying, “I will bring you the remainder tomorrow.” The transaction is valid for half of it, while the remainder has not entered his ownership and the contract concerning it is not valid. But if he gives him nothing, saying, “I will bring you the dirhams after the afternoon prayer, so give me the jewelry now,” the contract is invalid in its entirety. If the buyer says, “I do not have any dirhams, but I want to buy jewelry from you,” and the seller says, “I will lend you the money,” so he lends him ten thousand riyals, and he then returns them to