Sahih Muslim Book 10, Hadith Number 3886.

Chapter : Hoarding of foodstuff is forbidden.

Jabir b. ‘Abdullah (Allah be pleased with them) reported that he was travelling on his camel which had grown jaded, and he decided to let it off. When Allah’s Apostle (may peace be upon him) met him and prayed for him and struck it, so it trotted as it had never trotted before. He said: Sell it to me for an ‘uqaya. I said: No. He again said: Sell it to me. So I sold it to him for an ‘uqaya, but made the stipulation that I should be allowed to ride back to my family. Then when I came to (my place) I took the camel to him and he paid me its price in ready money. I then went back and he sent: (someone) behind me (and as I came) he said: Do you see that I asked you to reduce price for buying your camel. Take your camel and your coins; these are yours.