Ayesha reported,

The Messenger of Allah ﷺ married me when I was a girl of six. We then arrived in Medina and stayed among Banu Harith bin Khazraj. I fell ill with a fever and my hair fell out, then it grew back thick down to my shoulders.My mother Umm Ruman came to me while I was on a swing with some of my girlfriends. She called out to me, so I went to her, not knowing what she wanted. She took me by the hand and stood me at the door of the house while I was panting heavily. Once my breathing had settled a little, she took some water and wiped it over my face and head, then brought me inside the house. There were some women of the Ansar in a room, and they said, "May this be for goodness and blessing, and for the best of fortunes."She handed me over to them, and they prepared me. Then, to my surprise, the Messenger of Allah ﷺ came in the forenoon, and she handed me over to him. I was nine years old at that time.

Ibn Majah 1876

Sahih

حدثنا سويد بن سعيد حدثنا علي بن مسهر حدثنا هشام بن عروة عن أبيه

عن عائشة قالت

تزوجني رسول الله ﷺ وأنا بنت ست سنين فقدمنا المدينة فنزلنا في بني الحارث بن الخزرج فوعكت فتمرق شعري حتى وفى له جميمة فأتتني أمي أم رومان وإني لفي أرجوحة ومعي صواحبات لي فصرخت بي فأتيتها وما أدري ما تريد فأخذت بيدي فأوقفتني على باب الدار وإني لأنهج حتى سكن بعض نفسي ثم أخذت شيئا من ماء فمسحت به على وجهي ورأسي ثم أدخلتني الدار فإذا نسوة من الأنصار في بيت فقلن على الخير والبركة وعلى خير طائر فأسلمتني إليهن فأصلحن من شأني فلم يرعني إلا رسول الله ﷺ ضحى فأسلمتني إليه وأنا يومئذ بنت تسع سنين

ابن ماجه 1876صحيح
Contents
Reference
Commentary
Ayat
Collection
Sunan Ibn Majah
Book
Marriage
Chapter
Marriage of young girls given in marriage by their fathers
Numbering
Darussalam 1876
Ibn Majah 1876