Musnad Ahmad 5:16

Hassan ibn Musa narrated to us, Ibn Lahi'ah narrated to us, Abdullah ibn Hubayrah al-Saba'i narrated to us, from Abdullah ibn Zurayr al-Ghafiqi, from Ali, who said: The Messenger of Allah, peace and blessings of Allah be upon him, said: "A woman shall not be married [at the same time] as her paternal aunt, nor [at the same time] as her maternal aunt."