Abu Said al-Khudri narrates: “We were a few individuals, who, in a difficult and dangerous period, had shouldered the responsibility of guarding the Noble Prophet (s.a.w) in turn and according to a pre-determined schedule. After a period, some of us had become accustomed to speaking to each other softly and in whispers, including myself.
One night the Noble Prophet (s.a.w) approached us and, noticing some of us talking secretly and in whispers, said to us: “What is this secret conversation? Have you not been prohibited from this act? (when you confer together in private, do not give to each other counsel of sin and revolt and disobedience to the Messenger).””7
We pleaded: “We seek the forgiveness of Allah and His Prophet, (however), we were discussing about Dajjal.”
The Noble Prophet (s.a.w) said: “Should I inform you of one, whom I regard to be more dangerous than Dajjal?” He then said: “Concealed polytheism – that is, a person becomes a cause for the sins and evils of others. Danger from such a person is greater than that from Dajjal.”( Dastan-ha Wa Pand-ha, vol. 10, pg. 65, Tafsir Qur§ubi, vol. 9 )