The Prophet ﷺ reviewed him on the day of Uhud when he was fourteen years old and did not permit him to join the battle, then reviewed him again on the day of the Trench when he was fifteen years old and permitted him.
حدثنا أحمد بن حنبل حدثنا يحيى عن عبيد الله قال أخبرني نافع
أن النبي ﷺ عرضه يوم أحد وهو ابن أربع عشرة سنة فلم يجزه وعرضه يوم الخندق وهو ابن خمس عشرة سنة فأجازه
[Sahih]. Previously mentioned, no. 2957. Bukhari also related it, no. 4097, from the hadith of Yahya Qattan, and Muslim, no. 1868, from the hadith of Ubaydullah bin Umar, similarly.