When my father passed away, his loan was forgiven by one of our relatives and despite our repeated requests, they kept refusing to take it, but now, eighteen years later, they are demanding this amount and that too in the currency in which we did not borrow it. My question is, is it now our duty to repay his loan or not and if so, will it have to be given in the same currency in which he is demanding it?
If the details given in the question are really correct and based on facts, and there is no misrepresentation or falsehood involved, and in fact, after the death of the questioner's father, the said relative had forgiven the debt, for which the questioner also has witnesses, then it is not lawful according to Sharia to demand the debt again after eighteen years. And it is necessary to refrain from doing so.
کما فی الاشباہ والنظائر: أن الساقط لا يعود الخ ( ج 1 ص 274 )۔
وفی الفقہ الإسلامی وأدلتہ: ولكن يصح إبراء الدين الثابت في الذمة كضمان قيمة المغصوب المتلف، ويصح الإبراء عن الدعوى المتعلقة بالأعيان. ولا يصح إقالة الإبراء عن الدين ولا إقالة السلم؛ لأن الإبراء يسقط الدين من الذمة، والساقط لا يعود؛ لأنه معدوم، والمسلم فيه دين سقط. ويعد الإبراء من الدين تبرعاً؛ لأن فيه معنى التمليك، وإن كان في صورة إسقاط. الخ ( ج 6 ص 4370 )۔