Punishment of Disbelievers at War with Allah and His Apostle

Bukhari :: Book 8 :: Volume 82 :: Hadith 801

Narrated Abu Huraira:

The Prophet said, "The one who commits an illegal sexual intercourse is not a believer at the time of committing illegal sexual intercourse and a thief is not a believer at the time of committing theft and a drinker of alcoholic drink is not a believer at the time of drinking. Yet, (the gate of) repentance is open thereafter."