Certainly, that is how We deal with criminals. Truly, when it was said to them: "La ilaha illallah," they puffed themselves up with pride.
means, in this world they were too arrogant to say these words as the believers said them.
Ibn Abi Hatim narrated that Abu Hurayrah, may Allah be pleased with him, said that the Messenger of Allah said:
أُمِرْتُ أَنْ أُقَاتِلَ النَّاسَ حَتْى يَقُولُوا لاَ إِلَهَ إِلاَّ اللهُ فَمَنْ قَالَ لاَ إِلَهَ إِلاَّ اللهُ فَقَدْ عَصَمَ مِنِّي مَالَهُ وَنَفْسَهُ إِلاَّ بِحَقِّهِ وَحِسَابُهُ عَلَى اللهِ عَزَّ وَجَل
I have been commanded to fight the people until they say La ilaha ill-Allah. Whoever says La ilaha illallah, he and his property are safe from me except for his obligation, and his reckoning will be with Allah, may He be glorified.
Allah revealed in His Book the story of people who were arrogant, as He says:
إِنَّهُمْ كَانُوا إِذَا قِيلَ لَهُمْ لاَ إِلَهَ إِلاَّ اللَّهُ يَسْتَكْبِرُونَ
وَيَقُولُونَ أَيِنَّا لَتَارِكُوا الِهَتِنَا لِشَاعِرٍ مَّجْنُونٍ