﴿ وَمَا نُرِيهِم مِّنْ ءَايَةٍ إِلَّا هِىَ أَكْبَرُ مِنْ أُخْتِهَا ۖ وَأَخَذْنَٰهُم بِٱلْعَذَابِ لَعَلَّهُمْ يَرْجِعُونَ ﴾

“although each sign that We showed them was weigh­tier than the preceding one: and [each time] We took them to task through suffering, so that they might return [to Us].”

Please check ayah 43:50 for complete tafsir.