Sahih Muslim Book 31, Hadith Number 5946.
Chapter : The merits of Zubair and Talha (Allah be pleased with both of them).
‘Urwa reported: ‘Aisha said to me: Your fathers (Zubair and Abu Bakr) were amongst those about whom (it has been revealed): “Those who responded to the call of Allah and His Messenger after the misfortune had fallen upon them.”