Language:
كتاب النكاح
67
Wedlock, Marriage (Nikaah)
(40)
Chapter: The marrying of a daughter by her father to a ruler
(39)
باب تَزْوِيجِ الأَبِ ابْنَتَهُ مِنَ الإِمَامِ
وَقَالَ عُمَرُ خَطَبَ النَّبِيُّ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ إِلَيَّ حَفْصَةَ فَأَنْكَحْتُهُ.

Narrated `Aisha:

that the Prophet (ﷺ) married her when she was six years old and he consummated his marriage when she was nine years old. Hisham said: I have been informed that `Aisha remained with the Prophet (ﷺ) for nine years (i.e. till his death).

حَدَّثَنَا مُعَلَّى بْنُ أَسَدٍ، حَدَّثَنَا وُهَيْبٌ، عَنْ هِشَامِ بْنِ عُرْوَةَ، عَنْ أَبِيهِ، عَنْ عَائِشَةَ، أَنَّ النَّبِيَّ صلى الله عليه وسلم تَزَوَّجَهَا وَهْىَ بِنْتُ سِتِّ سِنِينَ، وَبَنَى بِهَا وَهْىَ بِنْتُ تِسْعِ سِنِينَ‏.‏ قَالَ هِشَامٌ وَأُنْبِئْتُ أَنَّهَا كَانَتْ عِنْدَهُ تِسْعَ سِنِينَ‏.‏
Reference : Sahih al-Bukhari 5134
In-book reference : Book 67, Hadith 70
USC-MSA web (English) reference : Vol. 7, Book 62, Hadith 65
  (deprecated numbering scheme)