Surat Tawbah (4-5)

{إِلاَّ الَّذِينَ عَاهَدتُّم مِّنَ الْمُشْرِكِينَ ثُمَّ لَمْ يَنقُصُوكُمْ شَيْئاً وَلَمْ يُظَاهِرُواْ عَلَيْكُمْ أَحَداً فَأَتِمُّواْ إِلَيْهِمْ عَهْدَهُمْ إِلَى مُدَّتِهِمْ إِنَّ اللّهَ يُحِبُّ الْمُتَّقِينَ} [التوبة: 4]

4- polytheists who did not break their promises and covenants with you are excluded from that punishment on condition that they should be loyal and keep to their promises without omitting something of it or providing help to any of your enemies. At that point, complete the period of their covenant to the end and do not treat them as traitors, for Allah loves those who keep their promises and covenants.

The tribe of Banu Damarah had only nine months of their covenant and they did not betray or break their covenant.

{فَإِذَا انسَلَخَ الأَشْهُرُ الْحُرُمُ فَاقْتُلُواْ الْمُشْرِكِينَ حَيْثُ وَجَدتُّمُوهُمْ وَخُذُوهُمْ وَاحْصُرُوهُمْ وَاقْعُدُواْ لَهُمْ كُلَّ مَرْصَدٍ فَإِن تَابُواْ وَأَقَامُواْ الصَّلاَةَ وَآتَوُاْ الزَّكَاةَ فَخَلُّواْ سَبِيلَهُمْ إِنَّ اللّهَ غَفُورٌ رَّحِيمٌ} [التوبة: 5]

5- When the four months during, which we prohibited the shedding of polytheists' blood, end, kill them whenever and wherever you find them. Capture, lock, watch, observe their movement, and besiege them in their forts. If they repent of their polytheism and error, establish Salah, and pay Zakah as a confirmation to their repentance and faith, leave them and do not harm them, for Allah forgives to whomever He wills and bestows mercy on whomever He wills because of their faith and obedience.

This Ayah is called "the Ayah of the sword."