Sura al-Tawbah 9:36

إِنَّ عِدَّةَ ٱلشُّهُورِ عِندَ ٱللَّـهِ ٱثْنَا عَشَرَ شَهْرًا فِى كِتَٰبِ ٱللَّـهِ يَوْمَ خَلَقَ ٱلسَّمَٰوَٰتِ وَٱلْأَرْضَ مِنْهَآ أَرْبَعَةٌ حُرُمٌ ذَٰلِكَ ٱلدِّينُ ٱلْقَيِّمُ فَلَا تَظْلِمُوا۟ فِيهِنَّ أَنفُسَكُمْ وَقَٰتِلُوا۟ ٱلْمُشْرِكِينَ كَآفَّةً كَمَا يُقَٰتِلُونَكُمْ كَآفَّةً وَٱعْلَمُوٓا۟ أَنَّ ٱللَّـهَ مَعَ ٱلْمُتَّقِينَ

inna ʿiddata l-shuhūri ʿinda allāhi thnā ʿashara shahran fī kitābi allāhi yawma khalaqa l-samāwāti wa-l-arḍa minhā arbaʿatun ḥurumun dhālika l-dīnu l-qayyimu fa-lā taẓlimū fī-hinna anfusakum wa-qātilū l-mushrikīna kāffatan ka-mā yuqātilūnakum kāffatan wa-iʿlamū annā allāha maʿa l-muttaqīna

The number of months in the sight of Allah is twelve (in a year)- so ordained by Him the day He created the heavens and the earth; of them four are sacred: that is the straight usage. So wrong not yourselves therein, and fight the Pagans all together as they fight you all together. But know that Allah is with those who restrain themselves.