5وَالَّذينَ سَعَوا في آياتِنا مُعاجِزينَ أُولٰئِكَ لَهُم عَذابٌ مِن رِجزٍ أَليمٌ(Saheeh International)But those who strive against Our verses [seeking] to cause failure1 – for them will be a painful punishment of foul nature. i.e., to undermine their credibility in order to defeat the Prophet (ṣ).