Musnad Ahmad 830:134

Abu Bakrah said: The Messenger of Allah (peace and blessings of Allah be upon him) said: "Men from among those who accompanied me and saw me will certainly come to the Basin (al-Hawd) to me. When they are raised up to me and I see them, they will be snatched away from me. I will surely say: 'My companions, my companions!' It will be said: 'You do not know what they introduced (innovated) after you.'"