Sayyiduna Abu Rafi' (may Allah be pleased with him) said: The Prophet (peace and blessings be upon him) borrowed a young camel from a man and said: "When the charity comes, we will repay you." When the charity came, he (peace and blessings be upon him) said to Abu Rafi': "Repay this man his camel." He looked and found only camels in their fourth year or older, so he went back to the Prophet (peace and blessings be upon him) and told him. He (peace and blessings be upon him) said: "Give that to him, for the best of people are those who repay their debts in the best manner."
Hadith Referenceالمعجم الكبير للطبراني / باب الألف / 910