Surah At-Taubah (The Repentance), Verse 5

فَاِذَا انْسَلَخَ الْاَشْهُرُ الْحُرُمُ فَاقْتُلُوا الْمُشْرِكِیْنَ حَیْثُ وَجَدْتُّمُوْهُمْ وَخُذُوْهُمْ وَاحْصُرُوْهُمْ وَاقْعُدُوْا لَهُمْ كُلَّ مَرْصَدٍ فَاِنْ تَابُوْا وَاَقَامُوا الصَّلٰوةَ وَاٰتَوُا الزَّكٰوةَ فَخَلُّوْا سَبِیْلَهُمْ اِنَّ اللّٰهَ غَفُوْرٌ رَّحِیْمٌ ۟

Fa izansalakhal Ashhurul Hurumu faqtulul mushrikeena haisu wajattumoohum wa khuzoohum wahsuroohum waq'udoo lahum kulla marsad; fa-in taaboo wa aqaamus Salaata wa aatawuz Zakaata fakhalloo sabeelahum; innal laaha Ghafoorur Raheem

“But when the forbidden months are past, then fight and slay the Pagans wherever ye find them, and seize them, beleaguer them, and lie in wait for them in every stratagem (of war); but if they repent, and establish regular prayers and practise regular charity, then open the way for them: for Allah is Oft-forgiving, Most Merciful.”

Quran 9:5 (Yusuf Ali Translation)