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 consumed that marriage when she was nine years old.
Reference: Sahih al-Bukhari 3896 In-book : Book 63, Hadith 122 USC-MSA web (English) : Vol. 5, Book 58, Hadith 236 (deprecated)
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