Quran 9:36 At-Tawbah, ayah 36 of 129

إِنَّ عِدَّةَ ٱلشُّهُورِ عِندَ ٱللَّهِ ٱثْنَا عَشَرَ شَهْرًا فِى كِتَـٰبِ ٱللَّهِ يَوْمَ خَلَقَ ٱلسَّمَـٰوَٰتِ وَٱلْأَرْضَ مِنْهَآ أَرْبَعَةٌ حُرُمٌ ۚ ذَٰلِكَ ٱلدِّينُ ٱلْقَيِّمُ ۚ فَلَا تَظْلِمُوا۟ فِيهِنَّ أَنفُسَكُمْ ۚ وَقَـٰتِلُوا۟ ٱلْمُشْرِكِينَ كَآفَّةً كَمَا يُقَـٰتِلُونَكُمْ كَآفَّةً ۚ وَٱعْلَمُوٓا۟ أَنَّ ٱللَّهَ مَعَ ٱلْمُتَّقِينَ ۝٣٦

9:36 Lo! the number of the months with Allah is twelve months by Allah's ordinance in the day that He created the heavens and the earth. Four of them are sacred: that is the right religion. So wrong not yourselves in them. And wage war on all of the idolaters as they are waging war on all of you. And know that Allah is with those who keep their duty (unto Him).