Sheikh Salman Al-Imad hafidahullah:

I say, may Allāh preserve and bless you, Abu Ishaq, this issue—firstly, the matter of selling a debt for another debt—is not prohibited in the absolute sense. There are many exceptions to this ruling. Alright, this issue has some ambiguity, and I will send you a very beneficial treatise regarding this matter for clarification (1). You will find it useful, inshaAllah. I will send it to you after this voice note, and it discusses an issue similar to the one we are currently discussing. In any case, the stronger opinion in this matter is that it does not fall under the category of selling a debt for a debt. It does not. Rather, it is closer to being considered a promise rather than a binding contract. Evidence for this is the possibility of reneging on such a promise. While this might cause harm to the restaurant owner, it is still considered a breach of promise and not a binding contract. Even if we were to consider it a contract, it would fall under the exceptions regarding the sale of something described in liability for another item described in liability. This is also known as Bay’ Al-Tasni’ (manufacture contract), where one requests someone to manufacture something, and the payment is deferred. This is one of the exceptions under the category of forward sales (Salam). It is stated that if the transaction does not involve Riba An-Nasi’ah in ribawi items—such as buying food with money—it is permissible to conduct such transactions on credit. However, if, for example, you buy food for food, this falls under the prohibition of Riba An-Nasi’ah and the prohibition of selling a debt for a debt may apply. However, food for money does not involve Riba An-Nasi’ah and is therefore permissible. This is an instance of selling something described and agreed upon, which is referred to as Bay’ At-Tasni’, where the payment is deferred until the product is delivered or collected. Based on this, and Allāh knows best, this transaction does not fall under the prohibited category of selling a debt for a debt. For further details, as you are a diligent student of knowledge, I will send you this treatise, inshaAllah, and I hope you will benefit from it. __ (1) صور بيع الدين بالدين التي انتقض فيها الإجماع https://t.me/madrasatuna/4361 #كتاب_البيوع