Abu Dawud Book 36, Hadith Number 4952.

Narated By ‘Aisha, Ummul Mu’minin : ‘Aisha said: Apostle of Allah! All my fellow-wives have kunyahs? He said: Give yourself the kunyah by Abdullah, your son – that is to say, her nephew (her sister’s son).

Musaddad said: Abdullah ibn az-Zubayr. She was called by the kunyah Umm Abdullah.