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