I passed by "Uthman bin "Affan in the mosque and greeted him with salam. He looked straight at me but did not return my greeting. I went to Ameer al-Mu"mineen "Umar bin al Khattab and said twice: “O Ameer al-Mu"mineen, has something new been introduced into Islam?” He said: “What has happened?” I said: “I passed by "Uthman just now in the mosque, and I greeted him with salam, and he looked straight at me but did not return my greeting.” "Umar sent for "Uthman and summoned him, and he said: “What prevented you from returning your brother"s greeting?” "Uthman said: “I did not do that.” I said: “Yes you did.” And he swore an oath and so did I. Then "Uthman remembered something and said: “Yes I did that; I ask Allah for forgiveness and repent to Him. You passed by me just when I was thinking to myself of something I heard from the Messenger of Allah (ﷺ). By Allah, I never remember it but my heart and my eyes are overwhelmed.” Sa"d (رضي الله عنه) said: “I will tell you what it is. The Messenger of Allah (ﷺ) was about to tell us the first du"a, then a Bedouin came and distracted him until the Messenger of Allah (ﷺ) got up and followed him when I got worried that he would reach his house before I could catch up with him. I stamped my foot on the ground. The Messenger of Allah (ﷺ) turned to me and said: “Who is this? Abu Ishaq?" I said: “Yes, O Messenger of Allah.” He said: "What is the matter?” I said: “Nothing, by Allah, except that you started to tell us about the first du"a, then this Bedouin came and distracted you.” He said: “Yes, the du"a of Dhun-Nun when he was in the belly of the fish: "La ilaha illa Anta[None has the right to be worshipped but You (O Allah)], Glorified (and Exalted) be You [above all that (evil) they associate with You]! Truly, I have been of the wrongdoers" (al-Anbiya’ [21:87]). No Muslim calls upon his Lord with it for anything but he will receive a response."