Daraqutni

Sayyiduna Abdullah bin Umar (may Allah be pleased with them both) narrates that on the day of the Battle of Uhud, I was presented before the Prophet Muhammad (peace be upon him), and at that time I was fourteen years old. He did not permit me to participate, as he did not consider me to have reached maturity. Then, on the occasion of the Battle of Khandaq, I was presented before him, and at that time I was fifteen years old, so he permitted me to participate. The narrator states: I informed Sayyiduna Umar bin Abdul Aziz about this, so he wrote to his government officials that they should pay a salary only to the person who has reached the age of fifteen. It was the practice of Sayyiduna Umar bin Abdul Aziz that he fixed a salary of one hundred dirhams for a boy of fifteen years. This narration is also transmitted with another chain of narration.