It occurs because Allah ordained Muhammad's raping little, prepubescent Aisha:
"My mother came to me while I was being swung on a swing between two branches and got me down. My nurse took over and wiped my face with some water and started leading me. When I was at the door she stopped so I could catch my breath. I was brought in while Muhammad was sitting on a bed in our house. My mother made me sit on his lap. The other men and women got up and left. The Prophet consummated his marriage with me in my house when I was nine years old” (Tabari 9:131).Sunnis can try to escape blame by scapegoating Shiites ("it's not us!"), but Sunni Islam is just as guilty of "sacralizing" child rape as the Ayatollah-in-hell.
"Narrated 'Aisha [Mohammed's six-year-old "bride" and nine-year-old sexual "partner"]: 'Allah's Apostle said (to me), "You were shown to me twice in (my) dream [before I married you]. Behold, a man was carrying you in a silken piece of cloth and said to me, 'She is your wife, so uncover her,' and behold, it was you. I would then say (to myself), 'If this is from Allah, then it must happen.'"'" (Bukhari Volume 9, Book 87, Number 139 and 140).
From here:
"'A man can marry a girl younger than nine years of age even if the girl is still a baby being breastfed. A man however is prohibited from having intercourse with a girl younger than nine other sexual act such as forplay rubbing kissing and sodomy is allowed. A man having intercourse with a girl younger than nine years of age has not comitted a crime but only an infraction if the girl is not permanently damaged. If the girl however is permanently damaged the man must provide for her all her life. But this girl will not count as one of the man s four permanent wives. He also is not permitted to marry the girl[']s sister.'"Speaking of 'Umdat al-Salik:
"There is no doubt that this translation is a valuable and important work, whether as a textbook for teaching Islamic jurisprudence to English speakers, or as a legal reference for use by scholars, educated laymen, and students in this language." Dr. Taha Jabir al-'Alwani, International Institute of Islamic Thought (Herndon, VA; December 1990)
"...We certify that this translation corresponds to the Arabic original and conforms to the practice and faith of the orthodox Sunni community (Ahl al-Sunnah wa al-Jama'a)." al-Azhar, the Muslim world's most prestigious institution of higher Islamic learning (Cairo; February, 1991).