AT TAUBAH — Ayat 37
إِنَّمَا النَّسِيءُ زِيَادَةٌ فِي الْكُفْرِ يُضَلُّ بِهِ الَّذِينَ كَفَرُواْ يُحِلِّونَهُ عَامًا وَيُحَرِّمُونَهُ عَامًا لِّيُوَاطِؤُواْ عِدَّةَ مَا حَرَّمَ اللّهُ فَيُحِلُّواْ مَا حَرَّمَ اللّهُ زُيِّنَ لَهُمْ سُوءُ أَعْمَالِهِمْ وَاللّهُ لاَ يَهْدِي الْقَوْمَ الْكَافِرِينَ
Indeed, the postponing [of restriction within sacred months] is an increase in disbelief by which those who have disbelieved are led [further] astray. They make it lawful one year and unlawful another year to correspond to the number made unlawful by Allah and [thus] make lawful what Allah has made unlawful. Made pleasing to them is the evil of their deeds; and Allah does not guide the disbelieving people.
Tafsir Ibnu Katsir
إِنَّمَا النَّسِىءُ زِيَادَةٌ فِى الْكُفْرِ يُضَلُّ بِهِ الَّذِينَ كَفَرُواْ يُحِلُّونَهُ عَامًا وَيُحَرِّمُونَهُ عَامًا لِّيُوَاطِئُواْ عِدَّةَ مَا حَرَّمَ اللَّهُ فَيُحِلُّواْ مَا حَرَّمَ اللَّهُ زُيِّنَ لَهُمْ سُوءُ أَعْمَـلِهِمْ وَاللَّهُ لاَ يَهْدِي الْقَوْمَ الْكَـفِرِينَ
37. 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 is made fair-seeming to them. And Allah guides not the people who disbelieve. Allah admonishes the idolators for choosing their wicked opinions over Allah's Law. They changed Allah's legislation based upon their vain desires, allowing what Allah prohibited and prohibiting what Allah allowed. They thought that three consecutive sacred months were rather long for them to remain without fighting, for they were full of anger and rage. This is why before Islam they innovated a change in the Sacred Month of Muharram, delaying it to the month of Safar! Therefore, they allowed fighting in the Sacred Month and made the non-sacred month sacred, to make the Sacred Months in a year four, as Allah decided! `Ali bin Abi Talhah said that Ibn `Abbas commented on Allah's statement,