(20) باب إِثْمِ الزُّنَاةِ
Narrated Abu Huraira:
The Prophet (ﷺ) 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."
Reference: Sahih al-Bukhari 6810
In-book reference: Book 86, Hadith 40
USC-MSA web (English) reference(deprecated numbering scheme): Vol. 8, Book 82, Hadith 801