Musnad Ahmad 30:2786

Muhammad ibn Ja‘far narrated to us, he said: Shu‘bah narrated to us, from ‘Ata’ ibn Abi Maymunah, he said: I heard Abu Rafi‘ narrating from Abu Hurayrah, from the Prophet, peace and blessings of Allah be upon him: "Zaynab’s name was Barrah, and it was said: 'She is purifying herself.' So the Messenger of Allah, peace and blessings of Allah be upon him, named her Zaynab."