Sahih Al Bukhari Hadith Number 871

Narrated Anas: The Prophet (peace be upon him) prayed in the house of Um Sulaim; and I, along with an orphan stood behind him while Um Sulaim (stood) behind us.

10  Call to Prayers (Adhaan)
Hadith number 871
Volume no 1
Chapter: 164 (The Salat (prayer) of women behind men)