Verse 18: If you persist in denial, so did ‘many’ communities before you. They were punished severely with a painful chastisement. Verse 21: He punishes whoever He wills and shows mercy to whoever He wills. And you will ‘all’ be turned back to Him. As Allah (swt) is ‘sattarul uyub’ and ‘ghaffaarudh dhunub’ he hides all our flaws, but on the Day of Judgement, it will all be different. The phrase ’You will all be turned back to Him’, means that when we will return to Allah, our secrets will no longer be ours