حَدَّثَنَا أَحْمَدُ بْنُ حَنْبَلٍ حَدَّثَنَا يَحْيَی عَنْ عُبَيْدِ اللَّهِ أَخْبَرَنِي نَافِعٌ عَنْ ابْنِ عُمَرَ أَنَّ النَّبِيَّ صَلَّی اللَّهُ عَلَيْهِ وَسَلَّمَ عُرِضَهُ يَوْمَ أُحُدٍ وَهُوَ ابْنُ أَرْبَعَ عَشْرَةَ فَلَمْ يُجِزْهُ وَعُرِضَهُ يَوْمَ الْخَنْدَقِ وَهُوَ ابْنُ خَمْسَ عَشْرَةَ سَنَةً فَأَجَازَهُ
سنن ابودوٗد · Hadith 2957
Narrated Nafi: That Ibn Umar was presented before the Prophet ﷺ on the day of Uhud, when he was fourteen years old, but he did not allow him. He was again presented to him on the day of Khandaq (the battle of Trench) when he was fifteen years old, he allowed him.
Sanad
حَدَّثَنَا أَحْمَدُ بْنُ حَنْبَلٍ حَدَّثَنَا يَحْيَی عَنْ عُبَيْدِ اللَّهِ أَخْبَرَنِي نَافِعٌ عَنْ ابْنِ عُمَرَ