Sunan an-Nasa'i, Hadith 3256 ⓘ
It was narrated that 'Aishah said: "The Messenger of Allah married me when I was seven years old, and he consummated the marriage with me when I was nine."
أَخْبَرَنَا مُحَمَّدُ بْنُ النَّضْرِ بْنِ مُسَاوِرٍ، قَالَ حَدَّثَنَا جَعْفَرُ بْنُ سُلَيْمَانَ، عَنْ هِشَامِ بْنِ عُرْوَةَ، عَنْ أَبِيهِ، عَنْ عَائِشَةَ، قَالَتْ تَزَوَّجَنِي رَسُولُ اللَّهِ صلى الله عليه وسلم لِسَبْعِ سِنِينَ وَدَخَلَ عَلَىَّ لِتِسْعِ سِنِينَ .
also referenced under: Book 26, Hadith 61 (In-Book) & Volume 4, Book 26, Hadith 3258 (DarusSalam)