وَإِذ تَأَذَّنَ رَبُّكُم لَئِن شَكَرتُم لَأَزيدَنَّكُم ۖ وَلَئِن كَفَرتُم إِنَّ عَذابي لَشَديدٌ

Your Lord declared, “If you are grateful, I will surely increase you; but if you are ungrateful, then My punishment is severe.”