Anas ibn Malik said, "A man came to the Prophet, may Allah blesshim and grant him peace, to ask him for a mount. He said, 'I will giveyou a she-camel's foal to ride.' He exclaimed, 'Messenger of Allah, whatcan I do with a she-camel's foal?' The Messenger of Allah, may Allah blesshim and grant him peace, said, 'Are camels born from anything other thanshe-camels?'"
English reference: Book 14, Hadith 268
Arabic reference: Book 1, Hadith 268