The Book of Faith (Kitab Al-Iman)
Muslim :: Book 1 : Hadith 109
It is narrated on the authority of Abu Huraira: A fornicator who fornicates is not a believer as long as he commits fornication, and no one who steals is a believer as long as he commits theft, and no one who drinks wine is a believer as long as he drinks it, and repentance may be accepted after that.