لِيُبَيِّنَ لَهُمُ الَّذي يَختَلِفونَ فيهِ وَلِيَعلَمَ الَّذينَ كَفَروا أَنَّهُم كانوا كاذِبينَ

This serves to clarify the matters they dispute and make those who disbelieve realize that they were liars.