Sunan An-Nasa'i - سنن النسائي
26. The Book of Marriage - كتاب النكاح
29) Chapter: A Man Marrying Off His Young Daughter
It was narrated from 'Aishah that the Messenger of Allah married her when she was six years old, and consummated the marriage with her when she was nine.
29) باب إِنْكَاحِ الرَّجُلِ ابْنَتَهُ الصَّغِيرَةَ .
أَخْبَرَنَا إِسْحَاقُ بْنُ إِبْرَاهِيمَ، قَالَ أَنْبَأَنَا أَبُو مُعَاوِيَةَ، قَالَ حَدَّثَنَا هِشَامُ بْنُ عُرْوَةَ، عَنْ أَبِيهِ، عَنْ عَائِشَةَ، أَنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم تَزَوَّجَهَا وَهِيَ بِنْتُ سِتٍّ وَبَنَى بِهَا وَهِيَ بِنْتُ تِسْعٍ .