Sayyiduna Sufyan bin Abdullah Thaqafi (may Allah be pleased with him) narrates: I submitted, "O Messenger of Allah (peace and blessings of Allah be upon you)! Please tell me about something which I may hold firmly." The Prophet (peace and blessings of Allah be upon him) said: "Say, 'My Lord is Allah,' and then remain steadfast." I submitted, "O Messenger of Allah (peace and blessings of Allah be upon you)! What do you fear most for me?" The narrator states: The Prophet (peace and blessings of Allah be upon him) held his tongue and then said: "This."

(Imam Ibn Hibban, may Allah have mercy on him, says:) The Prophet (peace and blessings of Allah be upon him) holding his tongue with his blessed hand and saying: "This." means that the Prophet (peace and blessings of Allah be upon him) intended to refer to the word "tongue." The Prophet (peace and blessings of Allah be upon him) knew about the matter which he had to teach the people, so the Prophet (peace and blessings of Allah be upon him) began with himself regarding acting upon that knowledge about which he was asked, and he informed the questioner that what he feared most for that person was this—that a person with a tongue can fall into difficulty. And he (peace and blessings of Allah be upon him) instructed him to keep control over his tongue and not to let it loose. Thus, the Prophet (peace and blessings of Allah be upon him) first acted upon what he had to teach, so that he (peace and blessings of Allah be upon him) could explain the ranks of knowledge and teaching in detail.