prohibition and the punishment

AN-NISA (WOMEN) : 15-18

4:15. If any of your women are guilty of lewdness, Take the evidence of four (Reliable) witnesses from amongst you against them; and if they testify, confine them to houses until death do claim them, or Allah ordain for them some (other) way.
4:16. If two men among you are guilty of lewdness, punish them both. If they repent and amend, Leave them alone; for Allah is Oft-returning, Most Merciful.

4:17. Allah accept the repentance of those who do evil in ignorance and repent soon afterwards; to them will Allah turn in mercy: For Allah is full of knowledge and wisdom.
4:18. Of no effect is the repentance of those who continue to do evil, until death faces one of them, and he says, "Now have I repented indeed;" nor of those who die rejecting Faith: for them have We prepared a punishment most grievous.