Abu Musa Ashari reported that he went to Umar bin Khattab and greeted him by saying: As-Salamu-Alaikum, here is Abdullah bin Qais (RA) , but he did not permit him (to get in). He (Abu Musa Ashari) again greeted him with as-Salamu-Alaikum and said: Here is Abu Musa, but he (Hadrat Umar) did not permit him (to get in). He again said: As-Salam-u-Alaikum, (and said) here is Ashari, (then receiving no response he came back). He (Hadrat Umar) said: Bring him back to me, bring him back to me. So he went there (in the presence of Hadrat Umar) and he said to him: Abu Musa, what made you go back, while we were busy in some work? He said: I heard Allahs Messenger ﷺ as saying: Permission should be sought thrice. And if you are permitted, (then get in), otherwise go back. He said: Bring witness to this fact, otherwise I shall do this and that, i. e. I shall punish you. Abu Musa went away and Umar said to him (on his departure): If he (Abu Musa) finds a witness he should meet him by the side of the pulpit in the evening and if he does not find a witness you would not find him there. When it was evening he (Hadrat Umar) found him (Abu Musa) there. He (Hadrat Umar) said: Abu Musa, have you been able to find a witness to what you have said? He said: Yes. Here is Ubayy bin Kab, whereupon he (Hadrat Umar) said: Yes, he is an authentic (witness). He (Hadrat Umar) said: Abu Tufail (the kunya of Ubayy bin Kab), what does he (Abu Musa) say? Thereupon he said: Ibn Khattab, I heard Allahs Messenger ﷺ as saying so. Do not prove to be a hard (task-master) for the Companions of Allahs Messenger ﷺ , whereupon he Hadrat Umar said: Hallowed be Allah. I had heard something (in this connection), but I wished it to be established (as an undeniable fact).