( فلنذيقن الذين كفروا عذابا شديدا ولنجزينهم أسوأ الذي ) يعني بأسوأ الذي ، أي : بأقبح الذي ، ( كانوا يعملون ) في الدنيا وهو الشرك بالله .
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.