Surah An-Nisa — Ayah 15 (4:15)

English translation (Saheeh International)

Those who commit immorality [i.e., unlawful sexual intercourse] of your women - bring against them four [witnesses] from among you. And if they testify,¹ confine them [i.e., the guilty women] to houses until death takes them or Allāh ordains for them [another] way.²

1. The witnesses must swear to actually having seen the act taking place.
2. The "other way" (i.e., penalty) was later revealed in 24:2, canceling the ruling in this verse.

Brief commentary

For those of your women who commit sexual offences – whether they are married or unmarried – call four trustworthy Muslim men witnesses. If they bear witness against them, then confine them to their homes as a punishment, until the end of their lives, or until Allah makes a way for them other than being confined. The ruling of this verse was replaced with the ruling that unmarried women who have illicit sexual relations should be whipped a hundred times and banished for a year, and married women who have illicit sexual relations should be stoned.