Sahih Bukhari
Sahih Bukhari Volume 001, Book 005, Hadith Number 288.
Hadith Section/Book: Sahih Bukhari Sahih Bukhari Book 05. Bathing (Ghusl)
Narated By 'Abdullah bin 'Umar : Umar bin Al-Khattab told Allah's Apostle, "I became Junub at night." Allah's Apostle replied, "Perform ablution after washing your private parts and then sleep."