"Prohibited to you (For marriage) are:- Your mothers, daughters, sisters; father's sisters, Mother's sisters; brother's daughters, sister's daughters; foster-mothers (Who gave you suck), foster-sisters; your wives' mothers; your step-daughters under your guardianship, born of your wives to whom ye have gone in,- no prohibition if ye have not gone in;- (Those who have been) wives of your sons proceeding from your loins; and two sisters in wedlock at one and the same time, except for what is past; for Allah is Oft-forgiving, Most Merciful;" - Quran 4:23 (read more)

"Narrated 'Aisha: that the Prophet married her when she was six years old and he consummated his marriage when she was nine years old, and then she remained with him for nine years (i.e., till his death)." - Sahih Bukhari 7:62:64 (read more)

"It is proven by the scholars who studied the Prophet’s biography in detail that he ate mutton that had been poisoned by a Jewish woman in Khaybar, ... When his final illness came, he (peace and blessings of Allaah be upon him) said: “O ‘Aa’ishah, I still feel the pain of the food that I ate in Khaybar, and this time I feel that my aorta is being cut from that poison.” Narrated by al-Bukhaari in his Saheeh. So there is no room for doubt that this poison affected his body, since it is proven in al-Saheeh and elsewhere." - Islam Q&A