Chapter 46: The Book of Cutting off the Hand of the Thief
It was narrated from abu Hurairah that the Prophet - and Ahmad said in his Hadith: "The Messenger of Allah said: 'No one who commits Zina is a believer at the moment when he is committing Zina; no one who steals is a believer at the moment when he is stealing; no one who drinks wine is a believer at the moment when he is drinking it; but repentance is available to him after that.
Sunan an-Nasa'i 4871