Is it permissible to act upon a dream to determine the value of a forgotten vow (nadhr), and what should one do to fulfill it?

If someone vows to donate a specific amount of money and then forgets it, they must strive to estimate the vowed amount and act upon what they most likely believe it to be. There is no harm in taking comfort from a dream, even if legal rulings are not established by it. If they later remember the amount and it was more than what they gave, they must complete the amount. If it was less, the extra amount given is a supererogatory charity. If they are unable to estimate the amount, they are obligated to donate the minimum amount that can be called "charity," such as one or two dinars, because the name applies to it.