Sahih al-Bukhari — Limits and Punishments set by Allah (Hudood) — Hadith No: 6782
Translation
Narrated Ibn `Abbas:The Prophet (ﷺ) said, "When (a person) an adulterer commits illegal sexual intercourse then he is not a believer at the time he is doing it; and when somebody steals, then he is not a believer at the time he is stealing