Sahih Bukhari Volume 7, Book 72, Hadith Number 801.

Narrated By Ibn ‘Abbas : Once I stayed overnight in the house of my aunt Maimuna bint Al-Harith and Allah’s Apostle was with her as it was her turn. Allah’s Apostle got up to offer the night prayer. I stood on his left but he took hold of my two locks of hair and made me stand on his right.