كتاب الحج
10  
The Book of Hajj
(233)
Chapter: The Obligation of Hajj (Pilgrimage) and its Excellence
(233)
- باب وجوب الحج وفضله
Riyad as-Salihin 1281
As-Sai'b bin Yazid (May Allah be pleased with him) reported:
I was seven years old when I was taken to perform Hajj (pilgrimage). This was during the time the Messenger of Allah (ﷺ) performed the Hajjat-ul-Wada' (Farewell Pilgrimage).

[Al- Bukhari].

وعن السائب بن يزيد رضي الله عنه، قال‏:‏ حج بي مع رسول الله صلى الله عليه وسلم في حجة الوداع وأنا ابن سبع سنين‏.‏ ‏(‏‏(‏رواه البخاري‏)‏‏)‏‏.‏
Reference : Riyad as-Salihin 1281
In-book reference : Book 10, Hadith 11