Sahih Al Bukhari Hadith Number 1926

Narrated `Aisha and Um Salama: At times Allah’s Messenger (peace be upon him) used to get up in the morning in the state of Janaba after having sexual relations with his wives. He would then take a bath and fast.

30  Fasting
Hadith number 1926
Volume no 3
Chapter: 22 (If a person observing Saum gets up in the morning in the state of Janaba)