Sahih al-Bukhari 4097
صحيح البخاري#4097Sahihحَدَّثَنَا يَعْقُوبُ بْنُ إِبْرَاهِيمَ، حَدَّثَنَا يَحْيَى بْنُ سَعِيدٍ، عَنْ عُبَيْدِ اللَّهِ، قَالَ أَخْبَرَنِي نَافِعٌ، عَنِ ابْنِ عُمَرَ ـ رضى الله عنهما أَنَّ النَّبِيَّ صلى الله عليه وسلم عَرَضَهُ يَوْمَ أُحُدٍ وَهْوَ ابْنُ أَرْبَعَ عَشْرَةَ فَلَمْ يُجِزْهُ، وَعَرَضَهُ يَوْمَ الْخَنْدَقِ وَهْوَ ابْنُ خَمْسَ عَشْرَةَ فَأَجَازَهُ.
Narrated Ibn `Umar:That the Prophet (ﷺ) inspected him on the day of Uhud while he was fourteen years old, and the Prophet (ﷺ) did not allow him to take part in the battle. He was inspected again by the Prophet (ﷺ) on the day of Al- Khandaq (i.e. battle of the Trench) while he was fifteen years old, and the Prophet (ﷺ) allowed him to take Part in the battle
Scholarly Authentication
The label above is the grade most of these scholars gave — one dissenting opinion no longer speaks for all of them. If any scholar calls a narration fabricated, that verdict is shown instead, whatever the others say. Each scholar's own wording:
Every narration in Sahih al-Bukhari is accepted as Sahih (authentic) by the established status of the book.
In-book reference: 64:141