Sahih al-Bukhari 3896
صحيح البخاري#3896SahihNarrated Hisham's father:Khadija died three years before the Prophet (ﷺ) departed to Medina. He stayed there for two years or so and then he married `Aisha when she was a girl of six years of age, and he consummated that marriage when she was nine years old
Scholarly Authentication
We show the most cautious grade (weakest-wins) as the overall label. Individual scholars graded it as follows:
Every narration in Sahih al-Bukhari is accepted as Sahih (authentic) by the established status of the book.
In-book reference: 63:121