Surah At-Tawbah, Verse 36

إِنَّ عِدَّةَ ٱلشُّهُورِ عِندَ ٱللَّهِ ٱثۡنَا عَشَرَ شَهۡرٗا فِي كِتَٰبِ ٱللَّهِ يَوۡمَ خَلَقَ ٱلسَّمَٰوَٰتِ وَٱلۡأَرۡضَ مِنۡهَآ أَرۡبَعَةٌ حُرُمٞۚ ذَٰلِكَ ٱلدِّينُ ٱلۡقَيِّمُۚ فَلَا تَظۡلِمُواْ فِيهِنَّ أَنفُسَكُمۡۚ وَقَٰتِلُواْ ٱلۡمُشۡرِكِينَ كَآفَّةٗ كَمَا يُقَٰتِلُونَكُمۡ كَآفَّةٗۚ وَٱعۡلَمُوٓاْ أَنَّ ٱللَّهَ مَعَ ٱلۡمُتَّقِينَ٣٦

inna ʿiddata l-shuhūri ʿinda l-lahi ith'nā ʿashara shahran fī kitābi l-lahi yawma khalaqa l-samāwāti wal-arḍa min'hā arbaʿatun ḥurumun dhālika l-dīnu l-qayimu falā taẓlimū fīhinna anfusakum waqātilū l-mush'rikīna kāffatan kamā yuqātilūnakum kāffatan wa-iʿ'lamū anna l-laha maʿa l-mutaqīna

Indeed, the number of months with Allāh is twelve [lunar] months in the register of Allāh [from] the day He created the heavens and the earth; of these, four are sacred. That is the correct religion [i.e., way], so do not wrong yourselves during them. And fight against the disbelievers collectively as they fight against you collectively. And know that Allāh is with the righteous [who fear Him].