Surah Fussilat — Ayah 27 (41:27)
فَلَنُذِيقَنَّ ٱلَّذِينَ كَفَرُواْ عَذَابٗا شَدِيدٗا وَلَنَجۡزِيَنَّهُمۡ أَسۡوَأَ ٱلَّذِي كَانُواْ يَعۡمَلُونَ ٢٧
English translation (Saheeh International)
But We will surely cause those who disbelieve to taste a severe punishment, and We will surely recompense them for the worst of what they had been doing.
Brief commentary
So we will definitely make those who disbelieved in Allah and rejected His messengers suffer from a severe punishment on the Day of Judgement. I will definitely requite them with a punishment for the worst of their actions, i.e. ascribing partners with Allah and sins.