Burden of proof

وَٱلَّـٰتِى يَأْتِينَ ٱلْفَـٰحِشَةَ مِن نِّسَآئِكُمْ فَٱسْتَشْهِدُوا۟ عَلَيْهِنَّ أَرْبَعَةً مِّنكُمْ ۖ فَإِن شَهِدُوا۟ فَأَمْسِكُوهُنَّ فِى ٱلْبُيُوتِ حَتَّىٰ يَتَوَفَّىٰهُنَّ ٱلْمَوْتُ أَوْ يَجْعَلَ ٱللَّهُ لَهُنَّ سَبِيلًا

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 Allāh ordains for them [another] way.

وَيَدْرَؤُا۟ عَنْهَا ٱلْعَذَابَ أَن تَشْهَدَ أَرْبَعَ شَهَـٰدَٰتٍۭ بِٱللَّهِ ۙ إِنَّهُۥ لَمِنَ ٱلْكَـٰذِبِينَ

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

أَمْ لَكُمْ كِتَـٰبٌ فِيهِ تَدْرُسُونَ

Or do you have a scripture in which you learn