I was presented to the Messenger of Allah ﷺ on the day of Uhud when I was fourteen years old, and he did not permit me to take part. Then I was presented to him on the day of the Trench when I was fifteen, and he permitted me.Nafi said, I narrated this to Umar bin Abdul-Aziz during his caliphate, and he said, "This is the dividing line between the minor and the adult."
حدثنا علي بن محمد حدثنا عبد الله بن نمير وأبو معاوية وأبو أسامة قالوا حدثنا عبيد الله بن عمر عن نافع
عرضت على رسول الله ﷺ يوم أحد وأنا ابن أربع عشرة سنة فلم يجزني وعرضت عليه يوم الخندق وأنا ابن خمس عشرة سنة فأجازني قال نافع فحدثت به عمر بن عبد العزيز في خلافته فقال هذا فصل ما بين الصغير والكبير
Bukhari related it in the Book of Testimonies, chapter on the coming of age of children and their testimony, number 2664, from the hadith of Abu Usama, from the hadith of Ubaydullah bin Umar, with this wording. Muslim related it in the Book of Governance, chapter explaining the age of coming of age, number 1868, from the hadith of Abdullah bin Numayr, with this wording.