"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)

"The interpretation of the verse "And those of your women as have passed the age of monthly courses, for them the 'Iddah (prescribed period), if you have doubt (about their periods), is three months; and for those who have no courses (i.e. they are still immature) their 'Iddah (prescribed period) is three months likewise". He said: The same applies to the 'idaah for girls who do not menstruate because they are too young, if their husbands divorce them after consummating the marriage with them." - al-Tabari