An-Nur 24:8

Wayadrao AAanha alAAathaba antashhada arbaAAa shahadatin billahiinnahu lamina alkathibeen

But it will prevent punishment from her if she gives four testimonies [swearing] by Allāh that indeed, he is of the liars.

And it will remove the punishment from the woman if she swears four oaths by Allah that he (the accuser husband) is certainly one of the liars,