Hisham bin Urwah said: Al-Zubayr (may Allah be pleased with him) accepted Islam at the age of sixteen, and he did not stay behind from any expedition of the Messenger of Allah (peace and blessings be upon him). When he was martyred he was in his sixties, and this happened at a distance of about one barid (a stage of travel) from Basrah.
Hadith Referenceالمعجم الكبير للطبراني / العشرة / 243