[Machine] Abu Musa sought permission from Umar three times, but Umar did not grant him permission. So Abu Musa returned and informed Umar of this. Umar asked him, "What prevented you?" Abu Musa replied, "I heard the Messenger of Allah ﷺ saying, 'If any one of you seeks permission three times and is not granted permission, then let him go back.'" Umar said, "Come to me with proof of this, or else Hammad will punish you." Abu Musa left and entered the mosque, then went to the gathering of the Ansar, and narrated to them the incident and what Umar said to him. They said, "None of us will stand with you except our youngest member." So Abu Sa'eed Al-Khudri stood with him and testified. Umar said to him, "We do not accuse you, but the narration from the Messenger of Allah ﷺ is severe."  

أَنَّ أَبَا مُوسَى اسْتَأْذَنَ عَلَى عُمَرَ ثَلَاثَ مَرَّاتٍ فَلَمْ يُؤْذَنْ لَهُ فَرَجَعَ فَبَلَغَ ذَلِكَ عُمَرَ فَقَالَ مَا رَدَّكَ؟ فَقَالَ إِنِّي سَمِعْتُ رَسُولَ اللَّهِ ﷺ يَقُولُ «إِذَا اسْتَأْذَنَ أَحَدُكُمْ ثَلَاثَ مَرَّاتٍ فَلَمْ يُؤْذَنْ لَهُ فَلْيَرْجِعْ» فَقَالَ لِتَجِئْنِي عَلَى هَذَا بِبَيِّنَةٍ وَإِلَّا قَالَ حَمَّادٌ تَوَعَّدَهُ قَالَ فَانْصَرَفَ فَدَخَلَ الْمَسْجِدَ فَأَتَى مَجْلِسَ الْأَنْصَارِ فَقَصَّ عَلَيْهِمُ الْقِصَّةَ مَا قَالَ لِعُمَرَ وَمَا قَالَ لَهُ عُمَرُ فَقَالُوا لَا يَقُومُ مَعَكَ إِلَّا أَصْغَرُنَا فَقَامَ مَعَهُ أَبُو سَعِيدٍ الْخُدْرِيُّ فَشَهِدَ فَقَالَ لَهُ عُمَرُ إِنَّا لَا نَتَّهِمُكَ وَلَكِنَّ الْحَدِيثَ عَنْ رَسُولِ اللَّهِ ﷺ شَدِيدٌ  

We were in the company of Ubayy b. Ka'b that Abu Musa Ash'ari came there in a state of anger. He stood (before us) and said: I ask you to bear witness in the name of Allah whether anyone amongst you heard Messenger of Allah ﷺ as saying: Permission (for entering the house) should be sought three times and if permission is granted to you (then get in). otherwise go back. Ubayy b. Ka'b said: What is the iiiatter? He said: I sought permission yesterday from 'Umar b. Khattab three times but he did not permit me, so I came back; then I went to him today and visited him and informed him that I had come to him yesterday and greeted him thrice, then came back, whereupon he said: Yes, we did hear you but be were at that time busy, but why did you not seek permission (further and you must have never gone back until you were permitted to do so). He said: I sought permission (in the manner) that I heard Messenger of Allah ﷺ having said (in connection 'With the seeking of permission for entering the house of a stranger). Thereupon he (Hadrat Umar) said: By Allah, I shall torture your back and your stomach unless you bring one who may bear witness to what you state. 'Ubayy b. Ka'b said: By Allah, none should stand with you (to bear testimony) but the youngest amongst us. And he therefore, said to Abu Sa'id: Stand up. So I stood up until I came to Umar and said: I heard Messenger of Allah ﷺ say this. (Using translation from Muslim 2153c)  

سَمِعَ أَحَدٌ مِنْكُمْ رَسُولَ اللَّهِ ﷺ يَقُولُ «الِاسْتِئْذَانُ ثَلَاثٌ فَإِنْ أُذِنَ لَكَ وَإِلَّا فَارْجِعْ»؟ قَالَ أُبَيٌّ وَمَا ذَاكَ؟ قَالَ اسْتَأْذَنْتُ عَلَى عُمَرَ بْنِ الْخَطَّابِ أَمْسِ ثَلَاثَ مَرَّاتٍ فَلَمْ يُؤْذَنْ لِي فَرَجَعْتُ ثُمَّ جِئْتُهُ فَدَخَلْتُ عَلَيْهِ فَأَخْبَرْتُهُ أَنِّي جِئْتُهُ أَمْسِ فَسَلَّمْتُ ثَلَاثًا ثُمَّ انْصَرَفْتُ فَقَالَ قَدْ سَمِعْنَاكَ وَنَحْنُ حِينَئِذٍ عَلَى شُغْلٍ فَلَوِ اسْتَأْذَنْتَ حَتَّى يُؤْذَنَ لَكَ؟ قَالَ اسْتَأْذَنْتُ كَمَا سَمِعْتُ رَسُولَ اللَّهِ ﷺ قَالَ فَوَاللَّهِ لَأُوجِعَنَّ ظَهْرَكَ أَوْ لَتَأْتِيَنِّي بِمَنْ يَشْهَدُ لَكَ عَلَى هَذَا قَالَ فَقَالَ أُبَيٌّ وَاللَّهِ لَا يَقُومُ مَعَكَ إِلَّا أَحْدَثُنَا سِنًّا قُمْ يَا أَبَا سَعِيدٍ فَقُمْتُ حَتَّى أَتَيْتُ عُمَرَ فَقُلْتُ قَدْ سَمِعْتُ رَسُولَ اللَّهِ ﷺ يَقُولُ هَذَا