(16) باب مَتَى يُفْرَضُ لِلرَّجُلِ فِي الْمُقَاتِلَةِ
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.
Reference: Sunan Abi Dawud 2957
In-book reference: Book 20, Hadith 30
English translation: Book 19, Hadith 2951