Tafseer Ibn Kathir of AN NUUR [8]

عَنْهَا الْعَذَابَ أَنْ تَشْهَدَ أَرْبَعَ شَهَادَاتٍ بِاللَّهِ إِنَّهُ لَمِنَ الْكَاذِبِينَ

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