Musannaf Ibn Abi Shayba 9:781

Abu Bakr narrated to us, from Husayn ibn Ali, from Za'idah, from Abd al-Aziz ibn Rufay', from Ibn Abi Mulaykah, who said: This verse was revealed: "And you will never be able to be equal [in feeling] between wives, even if you should strive [to do so]," regarding Aisha.