Sahih Muslim
The Book of Pilgrimage (Kitab Al-Hajj)
Book Number: 007 / Hadith Number: 3052
Jabir b. 'Abdullah (Allah be pleased with them) reported that he was asked about riding on a sacrificial animal, and he said: I heard Allah's Messenger (may peace be upon him) as saying: Ride on it gently, when you have need for it, until you find (another) mount.