His father gave him money to trade with and take a share of the profit, so the father died. What is due to the heirs?

Question:
Ahmad from Riyadh, go ahead, my brother Ahmad. Peace be upon you. Peace. If you please, Shaykh, I would like to ask, may Allah keep you well, about a man who took a sum of money from his father before his death, and his father said to him, “Increase this amount so that whatever profit comes in, you take a part and give me the rest.” After three years, his father passed away. He took this amount and put it in the bank in his account, and the amount grew until it became millions. He denied to his brothers that they had any right to it and that their father had not given him anything. So now, Shaykh, how should they proceed to prove their right, for example, and take from it? May Allah reward you with good and have mercy on your parents, if Allah wills?

Answer:
By Allah, my brother, if he and his father agreed that he would take money from his father’s wealth to work with and trade in, and the profit would be between them, then this is a mudarabah (profit-sharing partnership). They are bound by what they stipulated and what they contracted. As long as there is a dispute between him and the heirs, they should return to the Shari'ah court to resolve this dispute. Yes.