Nor is [the guarantor’s] knowledge of him required; rather, what is required is the guarantor’s consent.
His statement, “Nor of him”: it is not a condition that he know the beneficiary of the guarantee. This is very clear, since the beneficiary is the one who seeks out and investigates the guarantor; thus, it is not a condition that the guarantor know him.
Is it a condition that the guaranteed debt be known?
The answer is: it is not a condition that the guaranteed debt be known. Nevertheless, the more he knows about it, the better and the less likely problems are to arise; but this is not obligatory.
Thus, we now have: a guarantor, a guaranteed obligation, a beneficiary of the guarantee, and a guaranteed debtor. Knowledge of the beneficiary and the guaranteed debtor is not required, nor is knowledge of the guaranteed obligation—that is, the debt. Likewise, knowledge of the guarantor is not required either. Yet it is well known that the person entitled to the payment cannot be expected to accept a guarantor without knowing him, although the guarantee is nevertheless valid.
His statement, “Rather, the guarantor’s consent”: that is, the guarantor’s consent is taken into account. No one may be compelled to stand as guarantor; he must consent. If he does not consent, he cannot be held liable for the debt. Even if an unjust ruler wished to compel a certain person to guarantee another, he would not be bound by it. This is due to Allah’s statement concerning trade: “except when it is a trade conducted by mutual consent” [al-Nisa’ 4:29]. The Prophet ﷺ also said: “A sale is only valid by mutual consent” (1). The same applies to all contracts: consent is essential, except in the case of one who is lawfully compelled, such as a person placed under legal interdiction and the like.