Sunan Ibn Majah, Volume 3, Book 9, Hadith 1964 (DarusSalam) ⓘ
Maimunah bint Harith narrated: that the Messenger of Allah married her when he was Halal (not in Ihram). (Sahih).He (one of the narrators-Yazid) said: "And she was my maternal aunt and the maternal aunt of Idn 'Abbas also."
حَدَّثَنَا أَبُو بَكْرِ بْنُ أَبِي شَيْبَةَ، حَدَّثَنَا يَحْيَى بْنُ آدَمَ، حَدَّثَنَا جَرِيرُ بْنُ حَازِمٍ، حَدَّثَنَا أَبُو فَزَارَةَ، عَنْ يَزِيدَ بْنِ الأَصَمِّ، حَدَّثَتْنِي مَيْمُونَةُ بِنْتُ الْحَارِثِ، . أَنَّ رَسُولَ اللَّهِ ـ صلى الله عليه وسلم ـ تَزَوَّجَهَا وَهُوَ حَلاَلٌ . قَالَ وَكَانَتْ خَالَتِي وَخَالَةَ ابْنِ عَبَّاسٍ .
also referenced under: Hadith 1964 (Reference) & Book 9, Hadith 2040 (In-Book)