Sahih al-Bukhari, Hadith 5158 ⓘ

Narrated 'Urwa: The Prophet wrote the (marriage contract) with `Aisha while she was six years old and consummated his marriage with her while she was nine years old and she remained with him for nine years (i.e. till his death).

حَدَّثَنَا قَبِيصَةُ بْنُ عُقْبَةَ، حَدَّثَنَا سُفْيَانُ، عَنْ هِشَامِ بْنِ عُرْوَةَ، عَنْ عُرْوَةَ، تَزَوَّجَ النَّبِيُّ صلى الله عليه وسلم عَائِشَةَ وَهْىَ ابْنَةُ سِتٍّ وَبَنَى بِهَا وَهْىَ ابْنَةُ تِسْعٍ وَمَكَثَتْ عِنْدَهُ تِسْعًا‏.‏

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Key Source: Marriage to Aisha

Maybe one of the most controversial areas of Muhammed's life was his marriage to a child bride, Aisha. According to Muslim sources, Muhammad married her in his 50s, while she was 6 years old, and the marriage was consummated when she was 9 years old. This relationship in particular is seen...

Key Sources

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also referenced under: Book 67, Hadith 93 (In-Book) & Volume 7, Book 62, Hadith 88 (USC-MSA)