An example of pledging usufructs is for someone to say: “I pledge to you the usufruct of this house.” This is not valid, because it is not a tangible asset. Rather, we say: “Pledge the house itself.” If he says, “The house is an endowment and cannot be sold, so I will pledge its usufruct,” this is not valid.
An example involving a debt: I am owed ten thousand riyals by someone, so I seize him and say, “Give me ten thousand riyals.” He replies, “I do not have it.” I then say, “You are owed ten thousand riyals by someone else; make the debt owed to you a pledge for me.” In this case, a debt is being secured by another debt, so it is not valid. That is because the debt owed by the other person may not be sold except to the person who owes it; therefore, it cannot validly serve as a pledge.
It was also said that a debt may be secured by usufructs, and by another debt, because the objective is security. In the latter case, the second debtor is as though he were a guarantor, saying: “Yes, I am prepared to pay you what I owe so-and-so if he does not pay you.”
This is the correct view. It may be that my expectation of recovering the debt from what is owed by so-and-so is stronger than my expectation of recovering it from the original debtor. For example, someone sold this item to a man for one hundred thousand riyals. The buyer is insolvent, but he is owed a debt by a wealthy man, so he pledges that debt as security. He benefits from this pledge in that, when the payment falls due and the buyer does not pay him, he can go to the wealthy man, who will readily pay him that debt.
The same applies to usufructs. If he pledges to him the usufruct of this house, he may rent it out and take the rent as security; there is benefit in this. This is not an exchange transaction, such that we would say that the usufruct is unknown. Rather, it is a means of security: if he obtains something from it, then so be it; otherwise, he returns to the original asset against which this item was pledged. This is because we must understand a very beneficial principle: