Fulfilling the deceased's request which he made in a truthful dream
3-1-2018 | IslamWeb
Question:
Assalaamu alaykum. I saw my deceased father in a dream today, and he asked me to pay rs 900 to the mango vendor. I do not know which vendor it is in this case. Is there any alternative way I can pay off his debts to free him from Hellfire? Regards.
Answer:
All perfect praise be to Allah, the Lord of the worlds. I testify that there is none worthy of worship except Allah and that Muhammad, sallallaahu ‘alayhi wa sallam, is His slave and Messenger.
We ask Allah to confer His mercy upon your father, and we offer our condolences to your family.
As for the dream, we have already clarified in fatwas 18129 and 124331 that dreams do not establish religious rulings, so they do not make obligatory what is not an obligation.
Accordingly, you are not obliged to pay off your father's debt except if you volunteer to repay it out of kindness and dutifulness. The heirs are not obliged to pay off the deceased's debts from their own money unless they willfully choose to do so out of kindness.
If you wish to act upon what you saw in the dream, then there is no harm in doing so, because acting upon the truthful dream is permissible, as proven by the fact that Abu Bakr acted upon a dream in which a man saw Thaabit ibn Qays after his death asking him to do something for his sake. Abu Bakr 
executed the will of Thaabit ibn Qays.
It was narrated that Thaabit ibn Qays was martyred in the Battle of Yamaamah. One night, after his death, one of the Muslims saw Thaabit in a dream, saying to him, "I am Thaabit bin Qays, do you recognize me?" The man said, "Yes, I do", then Thaabit said, "I shall give you a piece of advice, so do not dare say that this is only a dream and leave what I say. When I was killed yesterday, a man from the Muslims passed by me and took my chain mail coat, and he is staying in one of the furthest houses. In front of his tent, there is a horse that he is preparing to be trained. On top of the armor is a twine on which is a saddle. Thus, go to Khaalid (the army commander) and tell him to send someone to retrieve it. Also, when you get back to Madeenah, tell the Caliph of the Messenger of Allah 
(Abu Bakr As-Siddeeq) that I owe so-and-so such-and-such, and to emancipate my slave so-and-so. Do not dare say that this is only a dream and leave what I say." The man woke up and went to Khaalid to tell him about his dream, so Khaalid sent someone to retrieve the chain mail armor suit, and he found it exactly where Thaabit had described it to be. Upon returning to Madeenah, Khaalid told Abu Bakr of the event and the dream of Thaabit, so Abu Bakr put it in Thaabit's will. Actually, nobody's will was altered and executed after his death besides Thaabit ibn Qays ." [Al-Haakim]
Shaykhul-Islam Ibn Taymiyyah 
wrote, "The will is valid if made in a true dream accompanied by circumstantial evidence indicating its truthfulness, as proven by the story of Thaabit ibn Qays's will which was executed by Abu Bakr 
." [Al-Ikhtiyaaraat]
If you cannot find the mango vendor, you can offer the sum of money in charity on his behalf.
Allah knows best.