Narrated 'Uthman:

(the son of Muhib) An Egyptian who came and performed the Hajj to the Kaba saw some people sitting. He enquire, "Who are these people?" Somebody said, "They are the tribe of Quraish." He said, "Who is the old man sitting amongst them?" The people replied, "He is 'Abdullah bin 'Umar." He said, "O Ibn Umar! I want to ask you about something;
please tell me about it. Do you know that 'Uthman fled away on the day (of the battle) of Uhud?" Ibn 'Umar said, "Yes." The (Egyptian) man said, "Do you know that 'Uthman was absent on the day (of the battle) of Badr and did not join it?" Ibn 'Umar said, "Yes." The man said, "Do you know that he failed to attend the Ar Ridwan pledge and did not witness it (i.e. Hudaibiya pledge of allegiance)?" Ibn 'Umar said, "Yes." The man said, "Allahu Akbar!" Ibn 'Umar said, "Let me explain to you (all these three things). As for his flight on the day of Uhud, I testify that Allah has excused him and forgiven him;
and as for his absence from the battle of Badr, it was due to the fact that the daughter of Allah's Apostle was his wife and she was sick then. Allah's Apostle ﷺ said to him, "You will receive the same reward and share (of the booty) as anyone of those who participated in the battle of Badr (if you stay with her).' As for his absence from the Ar-Ridwan pledge of allegiance, had there been any person in Mecca more respectable than 'Uthman (to be sent as a representative). Allah's Apostle would have sent him instead of him. No doubt, Allah's Apostle had sent him, and the incident of the Ar-Ridwan pledge of Allegiance happened after 'Uthman had gone to Mecca. Allah's Apostle held out his right hand saying, 'This is 'Uthman's hand.' He stroke his (other) hand with it saying, 'This (pledge of allegiance) is on the behalf of 'Uthman.' Then Ibn 'Umar said to the man, 'Bear (these) excuses in mind with you.'

حَدَّثَنَا مُوسَى بْنُ إِسْمَاعِيلَ، حَدَّثَنَا أَبُو عَوَانَةَ، حَدَّثَنَا عُثْمَانُ ـ هُوَ ابْنُ مَوْهَبٍ ـ قَالَ جَاءَ رَجُلٌ مَنْ أَهْلِ مِصْرَ حَجَّ الْبَيْتَ فَرَأَى قَوْمًا جُلُوسًا، فَقَالَ مَنْ هَؤُلاَءِ الْقَوْمُ قَالَ هَؤُلاَءِ قُرَيْشٌ. قَالَ فَمَنِ الشَّيْخُ فِيهِمْ قَالُوا عَبْدُ اللَّهِ بْنُ عُمَرَ. قَالَ يَا ابْنَ عُمَرَ إِنِّي سَائِلُكَ عَنْ شَىْءٍ فَحَدِّثْنِي هَلْ تَعْلَمُ أَنَّ عُثْمَانَ فَرَّ يَوْمَ أُحُدٍ قَالَ نَعَمْ. قَالَ تَعْلَمُ أَنَّهُ تَغَيَّبَ عَنْ بَدْرٍ وَلَمْ يَشْهَدْ قَالَ نَعَمْ. قَالَ تَعْلَمُ أَنَّهُ تَغَيَّبَ عَنْ بَيْعَةِ الرُّضْوَانِ فَلَمْ يَشْهَدْهَا قَالَ نَعَمْ. قَالَ اللَّهُ أَكْبَرُ. قَالَ ابْنُ عُمَرَ تَعَالَ أُبَيِّنْ لَكَ أَمَّا فِرَارُهُ يَوْمَ أُحُدٍ فَأَشْهَدُ أَنَّ اللَّهَ عَفَا عَنْهُ وَغَفَرَ لَهُ، وَأَمَّا تَغَيُّبُهُ عَنْ بَدْرٍ، فَإِنَّهُ كَانَتْ تَحْتَهُ بِنْتُ رَسُولِ اللَّهِ ﷺ وَكَانَتْ مَرِيضَةً، فَقَالَ لَهُ رَسُولُ اللَّهِ ﷺ " إِنَّ لَكَ أَجْرَ رَجُلٍ مِمَّنْ شَهِدَ بَدْرًا وَسَهْمَهُ ". وَأَمَّا تَغَيُّبُهُ عَنْ بَيْعَةِ الرُّضْوَانِ فَلَوْ كَانَ أَحَدٌ أَعَزَّ بِبَطْنِ مَكَّةَ مِنْ عُثْمَانَ لَبَعَثَهُ مَكَانَهُ فَبَعَثَ رَسُولُ اللَّهِ ﷺ عُثْمَانَ وَكَانَتْ بَيْعَةُ الرُّضْوَانِ بَعْدَ مَا ذَهَبَ عُثْمَانُ إِلَى مَكَّةَ، فَقَالَ رَسُولُ اللَّهِ ﷺ بِيَدِهِ الْيُمْنَى " هَذِهِ يَدُ عُثْمَانَ ". فَضَرَبَ بِهَا عَلَى يَدِهِ، فَقَالَ " هَذِهِ لِعُثْمَانَ ". فَقَالَ لَهُ ابْنُ عُمَرَ اذْهَبْ بِهَا الآنَ مَعَكَ.