The World Federation One Stop Fiqh

Ruling 2336

If a creditor pardons the guarantor of that he is owed, the guarantor cannot claim anything from the debtor. Similarly, if the creditor pardons some of it, he cannot claim that amount. However, if the creditor gives all or some of it as a gift (hibah) or calculates it as one-fifth tax (khums), alms tax (zakat), alms to the poor (ṣadaqah), or something similar, the guarantor can claim it from the debtor.