Sahih Muslim
The Book on Government (Kitab Al-Imara)
Book Number: 020 / Hadith Number: 4663
It has been narrated on the authority of Abu Mas'ud al-Ansari who said A man brought a muzzled she-camel and said: It is (offered) in the way of Allah. The Messenger of Allah (may peace be upon him) said: For this you will have seven hundred she-camels on the Day of Judgment all of which will be muzzled.