Sunan An-Nasa'i

It was narrated that Abu Hurairah said:""A man had lent a camel of a certain age to the Prophet and he came to get it back. He said: ""Give it to him"" But they could only find a camel that was older than it. He said: ""Give it to him."" He said: ""You have repaid me well,"" The Messenger of Allah said; ""The best of you is the one who is best in repaying