The Repentance
وَإِن نَّكَثُوٓا۟ أَيْمَـٰنَهُم مِّنۢ بَعْدِ عَهْدِهِمْ وَطَعَنُوا۟ فِى دِينِكُمْ فَقَـٰتِلُوٓا۟ أَئِمَّةَ ٱلْكُفْرِ ۙ إِنَّهُمْ لَآ أَيْمَـٰنَ لَهُمْ لَعَلَّهُمْ يَنتَهُونَ
And if they break their oaths after their treaty and defame your religion, then fight the leaders of disbelief, for indeed, there are no oaths [sacred] to them; [fight them that] they might cease.
Nearby ayahs help place verse 9:12 in sequence and meaning.
لَا يَرْقُبُونَ فِى مُؤْمِنٍ إِلًّا وَلَا ذِمَّةً ۚ وَأُو۟لَـٰٓئِكَ هُمُ ٱلْمُعْتَدُونَ
They do not observe toward a believer any pact of kinship or covenant of protection. And it is they who are the transgressors.
فَإِن تَابُوا۟ وَأَقَامُوا۟ ٱلصَّلَوٰةَ وَءَاتَوُا۟ ٱلزَّكَوٰةَ فَإِخْوَٰنُكُمْ فِى ٱلدِّينِ ۗ وَنُفَصِّلُ ٱلْـَٔايَـٰتِ لِقَوْمٍ يَعْلَمُونَ
But if they repent, establish prayer, and give zakah, then they are your brothers in religion; and We detail the verses for a people who know.
أَلَا تُقَـٰتِلُونَ قَوْمًا نَّكَثُوٓا۟ أَيْمَـٰنَهُمْ وَهَمُّوا۟ بِإِخْرَاجِ ٱلرَّسُولِ وَهُم بَدَءُوكُمْ أَوَّلَ مَرَّةٍ ۚ أَتَخْشَوْنَهُمْ ۚ فَٱللَّهُ أَحَقُّ أَن تَخْشَوْهُ إِن كُنتُم مُّؤْمِنِينَ
Would you not fight a people who broke their oaths and determined to expel the Messenger, and they had begun [the attack upon] you the first time? Do you fear them? But Allah has more right that you should fear Him, if you are [truly] believers.
قَـٰتِلُوهُمْ يُعَذِّبْهُمُ ٱللَّهُ بِأَيْدِيكُمْ وَيُخْزِهِمْ وَيَنصُرْكُمْ عَلَيْهِمْ وَيَشْفِ صُدُورَ قَوْمٍ مُّؤْمِنِينَ
Fight them; Allah will punish them by your hands and will disgrace them and give you victory over them and satisfy the breasts of a believing people