Musnad Ahmad 30:3581

Uthman ibn Umar narrated to us, Yunus informed us, from al-Zuhri, Qabisah ibn Dhu'ayb informed me, that Abu Hurayrah informed him that the Messenger of Allah (may Allah bless him and grant him peace) forbade combining a woman and her paternal aunt, and a woman and her maternal aunt [in marriage].