It was narrated from Hisham bin 'Urwah that his father said:
''Aishah said to me: 'O 'Urwah, your two fathers were of those who answered (the Call of) Allah and the Messenger (Muhammed) after being wounded," (they were) Abu Bakr and Zubair.'' (IT)
English reference (IT): Vol. 1, Book 1, Hadith 124 (IT)
Arabic reference (IT): Book 1, Hadith 129 (IT)