The Prophet (ﷺ) 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).
Sahih al-Bukhari Book 67, Hadith 93
← Previous Hadith The Prophet (ﷺ) said, "A prophet among the prophets went for a military expedition and said to his people: "A man who has married a lady and wants to consummate his marriage with her and he has not done so yet, should not accompany me.' "

Sahih al-Bukhari Book 67, Hadith 92 Next Hadith → The Prophet (ﷺ) stayed for three days at a place between Khaibar and Medina, and there he consummated his marriage with Safiyya bint Huyay. I invited the Muslims to a banquet which included neither meat nor bread. The Prophet (ﷺ) ordered for the leather dining sheets to be spread, and then dates, dried yogurt and butter were provided over it, and that was the Walima (banquet) of the Prophet. The Muslims asked whether Safiyya would be considered as his wife or as a slave girl of what his right hands possessed. Then they said, "If the Prophet (ﷺ) screens her from the people, then she Is the Prophet's wife but if he does not screen her, then she is a slave girl." So when the Prophet (ﷺ) proceeded, he made a place for her (on the camel) behind him and screened her from people.

Sahih al-Bukhari Book 67, Hadith 94