What should a man do who found the sum of three hundred pounds inside a pillow twenty-five years ago and spent it, and now wishes to be absolved of this matter?

The man who betrayed trust and took money must repent sincerely and return the amount (three hundred pounds) to its owner, or to his heirs if he is deceased. He must also ask for forgiveness from the owner of the money, for the Messenger of Allah, peace and blessings be upon him, said: "Whoever has wronged his brother in terms of his honor or property, let him seek his forgiveness before the Day when there will be neither dinar nor dirham. If he has good deeds, some of them will be taken from him; and if he has no good deeds, some of the sins of his companion will be taken and added to his sins." It is also recommended for him to treat the owner of the money kindly and compensate him as much as possible to appease him.