(This write-up has been prepared by the Hadīth Cell of Jāved Ahmad Ghāmidīwhich includes Moiz Amjad, Izhār Ahmad, Muhammad Aslam Najmi and Kaukab Shehzad)
روي أنه قال رجل من الصحابة لرسول الله صلى الله عليه وسلم: يا رسول الله قل لي في الإسلام قولا لا أسأل عنه أحدا بعدك. قال: قل آمنت بالله فاستقم. قال: يا رسول الله ما أكثر ما تخاف علي؟ فأخذ رسول الله صلى الله عليه وسلم بلسان نفسه ثم قال هذا.
It is narrated that one of the companions of the Prophet (sws) once asked the Prophet: "Prophet of God, give me a comprehensive directive of Islam, after which I need not ask any one else about it." The Prophet replied: "Say: I believe in the One God and then remain steadfast on it." He said: "Prophet of God, what is it that poses the greatest potential danger for me?" In response, the Prophet (sws) touched his tongue and said: "This".
Notes on the Text of the Narrative:
This narrative or a part of it, with minor variations, has been reported in Muslim (no. 38), Ibn Majah (no. 3972), Tirmidhī (No. 2410), Ahmad ibn Hanbal (nos. 15454, 15455, 15456, 15457, 19450), Dārimī (nos. 2710, 2711), Ibn Hibbān (no. 942, 5698, 5699, 5700, 5702), Nasā'ī's Sunan Al-Kubrā(nos. 11489) Ibn Abi Shaybah(no. 26501). Except where otherwise specified, the preferred text is the one reported in Muslim (no. 38).
In some narratives, as for instance in Ibn Majah(no. 3972) the words قل لي في الإسلام قولا (give me a comprehensive directive of Islam), have been replaced with حدثني بأمر أعتصم به (tell me about a matter of significance, which I should always abide by).
Some narrators have reported the word غيرك(ie. besides you) in place of بعدك(i.e. after you).
In some narratives, as for instance in Ibn Majah(no. 3972), the Prophet's response has been reported as قل ربي الله ثم استقم (Say: "My Lord is the One God" and then remain steadfast on it).
In some of the narratives, as for instance, Ahmad ibn Hanbal (no. 15455), the words ما أكثر ما تخاف علي؟ (what is it that poses the greatest potential danger for me) have been replaced by the words فأي شيء أتقي؟ (What is it that I should be most careful about).
The last part of the dialogue is reported in Ibn Majah(no. 3972).