Sahih Muslim Book - 38, Hadith - 5631

وحَدَّثَنِي مُحَمَّدُ بْنُ حَاتِمٍ ، حَدَّثَنَا يَحْيَى بْنُ سَعِيدٍ الْقَطَّانُ ، عَنِ ابْنِ جُرَيْجٍ ، حَدَّثَنَا عَطَاءٌ ، عَنْ عُبَيْدِ بْنِ عُمَيْرٍ ، أَنَّ أَبَا مُوسَى ، اسْتَأْذَنَ عَلَى عُمَرَ ثَلاَثًا ، فَكَأَنَّهُ وَجَدَهُ مَشْغُولاً ، فَرَجَعَ فَقَالَ عُمَرُ : أَلَمْ تَسْمَعْ صَوْتَ عَبْدِ اللهِ بْنِ قَيْسٍ ، ائْذَنُوا لَهُ ، فَدُعِيَ لَهُ ، فَقَالَ : مَا حَمَلَكَ عَلَى مَا صَنَعْتَ ، قَالَ : إِنَّا كُنَّا نُؤْمَرُ بِهَذَا قَالَ : لَتُقِيمَنَّ عَلَى هَذَا بَيِّنَةً ، أَوْ لأَفْعَلَنَّ ، فَخَرَجَ فَانْطَلَقَ إِلَى مَجْلِسٍ مِنَ الأَنْصَارِ ، فَقَالُوا : لاَ يَشْهَدُ لَكَ عَلَى هَذَا إِلاَّ أَصْغَرُنَا ، فَقَامَ أَبُو سَعِيدٍ فَقَالَ : كُنَّا نُؤْمَرُ بِهَذَا فَقَالَ عُمَرُ : خَفِيَ عَلَيَّ هَذَا مِنْ أَمْرِ رَسُولِ اللهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ ، أَلْهَانِي عَنْهُ الصَّفْقُ بِالأَسْوَاقِ.

It was narrated from 'Ubaid bin 'Umair that Abu Musil asked permission to enter upon 'Umar three times, and it was as if he found him busy, so he went back. 'Umar said: "Didn't we hear the voice of 'Abdullah bin Qais? Let him in." He was called and he said: "What made you do what you did?" He said: "That was enjoined upon us." He said: "Either you bring us proof for that or I will do such-and-such." He went to a gathering of the Ansar and they said: "No one will bear witness to that except the youngest of us." Abu Sa'eed stood up and said: "This was enjoined upon us." 'Umar said: "I missed out on this command of the Messenger of Allah (s.a.w) because of my business in the marketplace."