Surat At-Tawbah (123-124)

{يَا أَيُّهَا الَّذِينَ آمَنُواْ قَاتِلُواْ الَّذِينَ يَلُونَكُم مِّنَ الْكُفَّارِ وَلْيَجِدُواْ فِيكُمْ غِلْظَةً وَاعْلَمُواْ أَنَّ اللّهَ مَعَ الْمُتَّقِينَ} (التوبة : 123)

123- O believers, fight the disbelievers who are nearer to you and let them see harshness, power, and violence in fight, and know that Allah shall support those who fear Him.

{وَإِذَا مَا أُنزِلَتْ سُورَةٌ فَمِنْهُم مَّن يَقُولُ أَيُّكُمْ زَادَتْهُ هَـذِهِ إِيمَاناً فَأَمَّا الَّذِينَ آمَنُواْ فَزَادَتْهُمْ إِيمَاناً وَهُمْ يَسْتَبْشِرُونَ} (التوبة : 124)

124- When a Surah from the Qur'an is revealed to Prophet Muhammad (peace be upon him), some hypocrites said to one another in mockery: Who among you did benefit from this Ayah in faith or certainty?

As for the believers, indeed, the Ayah increases their faith and certainty while they are rejoicing because it shall increase their good deeds and degrees.