Narrated Aisha, Ummul Mu'minin: When we came to Medina, the women came to me when I was playing on the swing, and my hair were up to my ears. They brought me, prepared me, and decorated me. Then they brought me to the Apostle of Allah (peace_be_upon_him) and he took up cohabitation with me, when I was nine. Book 41, Number 4917
As an older man of fifty-plus years, Muhammad married a mere child of six years old and co-habited with her when she was 9 years old. As quoted above, the most trusted collections of hadiths establish the authenticity of this oral tradition. But still, Western Muslims are embarrassed by these hadiths. Sometimes they use a Weak hadith defense to excuse Muhammad's child marriage.