I ran over a sheep with my car

Q: One of my relatives came to me and told me that he was unable to face people anymore because he was in debt for a sum of forty thousand Riyals. He asked me to help him by guaranteeing him in buying a car through installment purchase, so that he may sell the car for cash, repay his debts, and save a sum to purchase a car for his personal use provided that he continues to pay the installments to only one party. I then guaranteed him to buy the car from Al-Dammam. The car value amounted to 142 thousand SR of which He paid 35 thousand SR as an advance payment, and the rest (107 thousand SR) to be distributed among forty installments of 2675 SR each. The payment of installments began in 7/1/1414 A.H.; however, he evaded paying them and I had to pay them, so I traveled several times to Ha'il. His elder brother also repaid a sum of 15950 RS for him. I then put the issue before my father - may Allah have mercy on him - (Part No. 14; Page No. 187) who talked to his brother and offered to take wheat in return for the sum I repaid. Thereupon, the elder brother accepted in spite of the guaranteed person's disagreement. Therefore, we received 57 tons of wheat from the farm of the guaranteed person that was worth (57 thousand RS) at that time. We stored this quantity in my uncle's name in the granaries. After two years, I received a sum of (1057397) riyals, dated 21/7/1418 A.H. which was (14689 RS) more than what I had paid. Am I entitled to take this additional sum as a substitute for the costs I incurred during travel from Al-Dammam to Hai'l to check the debts in Al-Dammam with the specific company in addition to the transport costs and the costs of transferring the wheat to the granaries and examining them? Or should I return that sum, or a part of it, to the guaranteed person or his elder brother? Given that I had informed his brother of this increment who said that he clears my father and me from this increment. However, I would like to ensure that my father (may Allah be merciful to him) and I are free from any liability.

A: If the case is as mentioned, it is impermissible for you to take profit from the wheat which exceeds the sum that you paid for the guaranteed indebted person as his agent; for the guaranteed person had given you the wheat to take what equaled the amount that you paid for him. Therefore, what is beyond that is the right of the wheat owner, if he is alive, and the right of his heirs in case of his death. If he grants it to you, then in this case you may have it. (Part No. 14; Page No. 188) May Allah grant us success. May peace and blessings be upon our Prophet Muhammad, his family, and Companions.