Sahih Bukhari Volume 9, Book 88, Hadith Number 172.

Narrated By Asma’ : The Prophet said, “I will be at my Lake-Fount (Kauthar) waiting for whoever will come to me. Then some people will be taken away from me whereupon I will say, ‘My followers!’ It will be said, ‘You do not know they turned Apostates as renegades (deserted their religion).'” (Ibn Abi Mulaika said, “Allah, we seek refuge with You from turning on our heels from the (Islamic) religion and from being put to trial”).