From Sahih Muslim (Hadith 5978):
Abdullah reported Allah's Messenger (ﷺ) as saying; I shall be there at the Cistern before you, and I shall have to contend for some people, but I shall have to yield. I would be saying:My Lord, they are my friends, they are my friends, and it would be said: You don't know what innovations they made after you
Reference: Muslim 5978