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.'' (ID)
English reference (ID): Vol. 1, Book 1, Hadith 124 (ID)
Arabic reference (ID): Book 1, Hadith 129 (ID)