إِنَّمَا ٱلنَّسِيٓءُ زِيَادَةٞ فِي ٱلۡكُفۡرِۖ يُضَلُّ بِهِ ٱلَّذِينَ كَفَرُواْ يُحِلُّونَهُۥ عَامٗا وَيُحَرِّمُونَهُۥ عَامٗا لِّيُوَاطِـُٔواْ عِدَّةَ مَا حَرَّمَ ٱللَّهُ فَيُحِلُّواْ مَا حَرَّمَ ٱللَّهُۚ زُيِّنَ لَهُمۡ سُوٓءُ أَعۡمَٰلِهِمۡۗ وَٱللَّهُ لَا يَهۡدِي ٱلۡقَوۡمَ ٱلۡكَٰفِرِينَ
Inna man naseee'u ziyaadatun filkufri yudallu bihil lazeena kafaroo yuhil loonahoo 'aamanw wa yuhar rimoonahoo 'aamal liyuwaati'oo 'iddata maa harramal laahu fayuhilloo maa harramal-laah; zuyyina lahum sooo'u a'maalihim; wallaahu laa yahdil qawmal kaafireen
Verily the transposing (of a prohibited month) is an addition to Unbelief: the Unbelievers are led to wrong thereby: for they make it lawful one year, and forbidden another year, in order to adjust the number of months forbidden by Allah and make such forbidden ones lawful. The evil of their course seems pleasing to them. But Allah guideth not those who reject Faith.
— At-Taubah (ٱلتَّوْبَة), 9:37