This is no surprise. Islamic tradition records that Muhammad consummated his marriage with Aisha when she was nine, and the resultant fact that child marriage is accepted in wide swaths of the Islamic world. Child marriage has abundant attestation in Islamic tradition and law.
Turkey’s directorate of religious affairs (Diyanet) said in January 2018 that under Islamic law, girls as young as nine can marry.
“Islam has no age barrier in marriage and Muslims have no apology for those who refuse to accept this” — Ishaq Akintola, professor of Islamic Eschatology and Director of Muslim Rights Concern, Nigeria
“There is no minimum marriage age for either men or women in Islamic law. The law in many countries permits girls to marry only from the age of 18. This is arbitrary legislation, not Islamic law.” — Dr. Abd Al-Hamid Al-‘Ubeidi, Iraqi expert on Islamic law
There is no minimum age for marriage and that girls can be married “even if they are in the cradle.” — Dr. Salih bin Fawzan, prominent cleric and member of Saudi Arabia’s highest religious council
“Islam does not forbid marriage of young children.” — Pakistan’s Council of Islamic Ideology
Hadiths that Muslims consider authentic record that Muhammad’s favorite wife, Aisha, was six when Muhammad wedded her and nine when he consummated the marriage:
“The Prophet 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)” (Bukhari 7.62.88).
Muhammad was at this time fifty-four years old.
Marrying young girls was not all that unusual for its time, but because in Islam Muhammad is the supreme example of conduct (cf. Qur’an 33:21), he is considered exemplary in this unto today. And so in April 2011, the Bangladesh Mufti Fazlul Haque Amini declared that those trying to pass a law banning child marriage in that country were putting Muhammad in a bad light: “Banning child marriage will cause challenging the marriage of the holy prophet of Islam, [putting] the moral character of the prophet into controversy and challenge.” He added a threat: “Islam permits child marriage and it will not be tolerated if any ruler will ever try to touch this issue in the name of giving more rights to women.” The Mufti said that 200,000 jihadists were ready to sacrifice their lives for any law restricting child marriage.