It was narrated from Abu Hurairah (RA) that the Messenger of Allah (SAW) said:
“The adulterer, at the time he is committing adultery, is not a believer; (the wine drinker) at the time he is drinking, is not a believer; the thief, at the time he is stealing, is not a believer; the plunderer, at the time he is plundering with the people looking on, is not a believer.”
(Sunan Ibn Majah 3936, Book 36, Hadith 11)