What is the ruling on returning 55 Egyptian Pounds I took from my brother as compensation for a damaged phone SIM card, knowing that I suspect the source of the money, and when should it be returned?

If a brother damages his brother's phone due to his own negligence, he is liable for what he damaged. As for collecting what is owed from his money, no attention is paid to doubt regarding the source of the money, for the default presumption is that what a person possesses is his property. If the matter goes beyond doubt to a strong presumption or certain knowledge, then unlawful money is of two types: unlawful in its essence, such as stolen or usurped money; this type may not be used to collect what is owed and must be returned. The second type is unlawful due to its earning; this type may be used to collect what is owed because the sin is related to the earner's responsibility, not the money itself.