Sayyiduna Zayd bin Jariyah (may Allah be pleased with him) said that on the day of Uhud the Messenger of Allah (peace and blessings be upon him) considered some people too young and did not accept them (for jihad). Among them was I, and Sayyiduna al-Bara' bin Azib, Sayyiduna Zayd bin Arqam, Sayyiduna Sa'd Abu Sa'id al-Khudri and Sayyiduna Ibn Umar (may Allah be pleased with them), and (the narrator) also mentioned Sayyiduna Jabir bin Abdullah (may Allah be pleased with him).
In my book (the narrator's name) is given thus as Uthman bin Abdullah, and in another place I saw it as Ibn Ubaydullah.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب السير / 17809