9:37
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.
The term refers to the practice of postponing or transferring the sanctity of a sacred month to another month. In pre-Islamic Arabian custom, four months were designated as sacred—Muḥarram, Rajab, Dhū al-Qaʿdah, and Dhū al-Ḥijjah—during which warfare was prohibited. The practice of postponement involved declaring other months to be sacred while treating the originally designated sacred months as ordinary. This alteration undermined the intended purpose of the sacred months, which was to ensure security and peace for a fixed period each year. Three of these months occur consecutively, while the fourth, Rajab, is separated from them, thereby creating at least two intervals during the year when hostilities would cease. These intervals increased the possibility of ending conflicts and facilitating negotiations for peace. In contemporary terms, this arrangement may be understood as a form of enforced ceasefire within the traditional Arabian calendar system.
References:
NOORUDDÎN ,ALLÂMAH. (2015). Exegesis of The Holy Qur’ân Commentary and Reflections.