Musnad Abu Ya'la al-Mawsili 152:131

And with his chain of narration from Abdullah, he said: The Messenger of Allah (ﷺ) said: "I am your forerunner at the Hawd (the Cistern). And I will certainly dispute with some people, then I will certainly be overcome regarding them. So I will say: 'O my Lord, my companions!' Then He will say: 'Indeed, you do not know what they innovated after you.'"