Sahih Muslim
The Book of Jihad and Expedition (Kitab Al-Jihad wal-Siyar)
Book Number: 019 / Hadith Number: 4318
It is narrated on the authority of Anas that the Messenger of Allah (may peace be upon him) said on the day of the Battle of Ubud: O Allah, if Thou wilt (defeat Muslims), there will be none on the earth to worship Thee.