Sahih Bukhari | Volume 8 | Hadith Number 584

Narrated by Anas
The Prophet said, "Some of my companions will come to me at my Lake Fount, and after I recognize them, they will then be taken away from me, whereupon I will say, 'My companions!' Then it will be said, 'You do not know what they innovated (new things) in the religion after you."