Surah Al-Mujadila 58:15

أَعَدَّ ٱللَّهُ لَهُمْ عَذَابًا شَدِيدًا ۖ إِنَّهُمْ سَآءَ مَا كَانُوا۟ يَعْمَلُونَ

Allāh has prepared for them a severe punishment. Indeed, it was evil that they were doing.

Translation: Saheeh International

Tafsir

God has prepared for them a severe chastisement. Evil indeed is that which they are wont to do in the way of acts of disobedience.

Excerpt from Tafsir al-Jalalayn, commentary on 58:15, via Quran.com. The reader has the full commentary and 9 more tafsirs.