Asking permission three times

'Ubayd ibn 'Umayr reported that Abu Musa al-Ash'ari asked permission of 'Umar ibn al-Khattab, but he did not grant him permission. It seemed that he was busy. Abu Musa came back and 'Umar had finished. He said, "Didn't I hear the voice of 'Abdullah ibn Qays? Give him permission to enter." He was told, "He has gone away," so he sent after him. Abu Musa said, "We were commanded to behave like that (i.e. to go away after having asked permission to enter three times)." 'Umar said, "Bring me a clear proof of it." He then went to the gathering of the Ansar and questioned them. They said, "Only the youngest of us will attest to that - Abu Sa'id al-Khudri." He went with Abu Sa'id. 'Umar said, "Is something of what the may Allah bless him and grant him peace, ﷺ commanded hidden from me? Doing business in the markets distracted me," i.e. going out to trade.

حَدَّثَنَا مُحَمَّدُ بْنُ سَلاَمٍ، قَالَ: أَخْبَرَنَا مَخْلَدٌ، قَالَ: أَخْبَرَنَا ابْنُ جُرَيْجٍ قَالَ: أَخْبَرَنِي عَطَاءٌ، عَنْ عُبَيْدِ بْنِ عُمَيْرٍ، أَنَّ أَبَا مُوسَى الأَشْعَرِيَّ اسْتَأْذَنَ عَلَى عُمَرَ بْنِ الْخَطَّابِ، فَلَمْ يُؤَذَنْ لَهُ، وَكَأَنَّهُ كَانَ مَشْغُولاً، فَرَجَعَ أَبُو مُوسَى، فَفَرَغَ عُمَرُ فَقَالَ: أَلَمْ أَسْمَعْ صَوْتَ عَبْدِ اللهِ بْنِ قَيْسٍ؟ إِيذَنُوا لَهُ، قِيلَ: قَدْ رَجَعَ، فَدَعَاهُ، فَقَالَ: كُنَّا نُؤْمَرُ بِذَلِكَ، فَقَالَ: تَأْتِينِي عَلَى ذَلِكَ بِالْبَيِّنَةِ، فَانْطَلَقَ إِلَى مَجْلِسِ الأَنْصَارِ فَسَأَلَهُمْ، فَقَالُوا: لاَ يَشْهَدُ لَكَ عَلَى هَذَا إِلاَّ أَصْغَرُنَا: أَبُو سَعِيدٍ الْخُدْرِيُّ فَذَهَبَ بِأَبِي سَعِيدٍ، فَقَالَ عُمَرُ: أَخَفِيَ عَلَيَّ مِنْ أَمْرِ رَسُولِ اللهِ ﷺ؟ أَلْهَانِي الصَّفْقُ بِالأَسْوَاقِ، يَعْنِي الْخُرُوجَ إِلَى التِّجَارَةِ.