Surat At-Tawbah - سورة التوبة

إِنَّمَا النَّسِيءُ زِيَادَةٌ فِي الْكُفْرِ ۖ يُضَلُّ بِهِ الَّذِينَ كَفَرُوا يُحِلُّونَهُ عَامًا وَيُحَرِّمُونَهُ عَامًا لِّيُوَاطِئُوا عِدَّةَ مَا حَرَّمَ اللَّهُ فَيُحِلُّوا مَا حَرَّمَ اللَّهُ ۚ زُيِّنَ لَهُمْ سُوءُ أَعْمَالِهِمْ ۗ وَاللَّهُ لَا يَهْدِي الْقَوْمَ الْكَافِرِينَ

Muhsin Khan: The postponing (of a Sacred Month) is indeed an addition to disbelief: thereby the disbelievers are led astray, for they make it lawful one year and forbid it another year in order to adjust the number of months forbidden by Allah, and make such forbidden ones lawful. The evil of their deeds seems pleasing to them. And Allah guides not the people, who disbelieve.