Sayyiduna Ka'b bin Ujrah (may Allah be pleased with him) said: The Messenger of Allah (peace and blessings be upon him) came out to us while I was the seventh of seven men, and he (peace and blessings be upon him) said: "After me there will be rulers," then he mentioned a similar hadith.
Hadith Referenceالمعجم الكبير للطبراني / باب الكاف / 16345