وَالّٰتِيْ يَأْتِيْنَ الْفَاحِشَةَ مِنْ نِّسَاۤىِٕكُمْ فَاسْتَشْهِدُوْا عَلَيْهِنَّ اَرْبَعَةً مِّنْكُمْ ۚ فَاِنْ شَهِدُوْا فَاَمْسِكُوْهُنَّ فِى الْبُيُوْتِ حَتّٰى يَتَوَفّٰىهُنَّ الْمَوْتُ اَوْ يَجْعَلَ اللّٰهُ لَهُنَّ سَبِيْلًا ( النساء: ١٥ )
Wallaatee yaateenal faahishata min nisaaa'ikum fastashhidoo 'alaihinna arba'atam minkum fa in shahidoo fa amsikoohunna fil buyooti hatta yatawaffaa hunnal mawtu aw yaj'alal laahu lahunna sabeelaa (an-Nisāʾ 4:15)
Those who commit immorality [i.e., unlawful sexual intercourse] of your women – bring against them four [witnesses] from among you. And if they testify, confine them [i.e., the guilty women] to houses until death takes them or Allah ordains for them [another] way. (An-Nisa  : 15)
1 Mufti Taqi Usmani
Those of your women who commit the shameful act, have four witnesses (against them) from among you. So, if they testify, then confine those women to their homes until death overcomes them, or Allah prescribes a way for them.