حَدَّثَنَا يَحْيَى عَنْ عُبَيْدِ اللَّهِ أَخْبَرَنِي نَافِعٌ عَنِ ابْنِ عُمَرَ أَنَّ النَّبِيَّ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ عَرَضَهُ يَوْمَ أُحُدٍ وَهُوَ ابْنُ أَرْبَعَ عَشْرَةَ فَلَمْ يُجِزْهُ ثُمَّ عَرَضَهُ يَوْمَ الْخَنْدَقِ وَهُوَ ابْنُ خَمْسَ عَشْرَةَ فَأَجَازَهُ
مسند امام احمد بن حنبل · Hadith 4661
It was narrated from Ibn 'Umar that the Prophet (PBUH) inspected him on the day of Uhud, when he was fourteen years old, and he did not allow him (to take part in the fighting). Then he inspected him on the day of al-Khandaq, when he was fifteen years old, and he allowed him (to take part in the fighting).
Translated by Dr. Muhammad Muhsin Khan · Reviewed by Islamic University of Madinah · Published March 2020