If the debtor is poor, it is not permissible for the creditor to demand his right from him, with evidence.

The Shaykh : We say that if the debtor is poor, it is not permissible for the creditor to demand his right from him, nor to press him for it, nor to detain him over it. The evidence for this is the saying of Allah the Exalted: meaning that if the debtor is in difficulty, meaning he is unable to pay, then you should grant him a respite until Allah makes him wealthy. As for the second part of the hadith, what is it about in terms of goodness? It is about the goodness of collection, which is that a person should be easy in his dealings. So if someone comes to demand his right from a person and says, "I want to assign you to a debt I have with so-and-so," and this person who owes the debt is wealthy, meaning capable of paying with his money and his body, then from the goodness of collection is that you accept it. And if you accept it, Allah will reward you for that for your obedience to the command of the Prophet (peace and blessings be upon him) and for your kindness to your companion. Note the example: A man demands a thousand riyals from a person, so he comes to him to demand it and says, "I have a thousand riyals with Zayd, and I want to assign you to him." What is prescribed for the creditor? It is prescribed for him, if the assignee is wealthy, to accept it due to the command of the Prophet (peace and blessings be upon him) regarding that. If he accepts, the right transfers from the assignor to the assignee, and the assignor is absolved.