Question Summary:
Marriage of Aisha, radiyallahu ‘anhaa.

Question Detail:

AsSalamuAlaykumWaRahmatullahiWaBarakatuhuWaJannatuhu:
I have been asked sevral times by muslim and non muslism that: 
Why Prophet Muhammad married Aisha when she was only 9

Answer :

In the Name of Allah, the Most Gracious, the Most Merciful.
As-salāmu ‘alaykum wa-rahmatullāhi wa-barakātuh.
 
Please refer to the following two articles concerning this subject:
Askimam Article - Young Marriage
Askimam Article - The Age of Aishah (radiyallahu `anha) at the Time of Marriage
 
 
And Allah Ta’āla Knows Best
Muhammad Haris Siddiqui
Student Darul Iftaa
Melbourne, Australia 
Checked and Approved by,
Mufti Ebrahim Desai.