Verse 22

ذَٰلِكَ بِأَنَّهُمْ كَانَت تَّأْتِيهِمْ رُسُلُهُم بِٱلْبَيِّنَـٰتِ فَكَفَرُوا۟ فَأَخَذَهُمُ ٱللَّهُ إِنَّهُۥ قَوِىٌّ شَدِيدُ ٱلْعِقَابِ

This is because when indeed their messengers went to them with proofs, they rejected faith, consequently, God punished them. Indeed He is All Powerful, strict in enforcing punishment.