What is the recourse for a guarantor who pays a debt when the debtor and another guarantor are jointly liable?
Chapter on Guarantee (Daman)
Al-Mughni
Book of Assignment (Transfer of Debt)
Primary text
If two men owe one hundred units, each being responsible for half, and each guarantees the other for his share, and a third party guarantees one of them for the full hundred with his permission and pays it, the right against all parties is extinguished. The third party guarantor has the right to recourse only against the one whose debt he guaranteed (the primary debtor), as he did not guarantee the other party, nor did he authorize that other party's payment. Upon recovering from the one whose debt he guaranteed, the latter then has recourse against the original co-guarantor for his half, provided the original co-guarantor had authorized the payment of that half.
Supporting text
A second narration permits the third party guarantor recourse against the other original debtor for the full hundred because the debt became due from him to the one who discharged it on his behalf, granting the right of recourse as if he were the original creditor.