What is the ruling on intercourse with a disbelieving woman? And how does one repent?

Adultery is an act of lewdness in the front or back passage, and it is one of the gravest major sins. Muslims have unanimously agreed on its prohibition, based on the Almighty's saying: {And do not approach unlawful sexual intercourse. Indeed, it is ever an indecency and an evil way.} [Quran 17:32], and His saying: {And those who do not invoke with Allah another deity or kill the soul which Allah has forbidden them to kill, except by right, and do not commit unlawful sexual intercourse. And whoever does that will meet a penalty. The punishment will be multiplied for him on the Day of Resurrection, and he will abide therein humiliated.} [Quran 25:68-69].

The prohibition of adultery includes women, whether they are disbelievers or Muslims. It is obligatory for anyone who commits this major sin to repent and conceal their deed.