the intercalation is an act of gross infidelity which causes the unbelievers to be led further astray. they declare a month to be lawful in one year and forbidden in another year in order that they may conform to the number of months that allah has declared as sacred and at the same time make lawful what allah has forbidden. their foul acts seem fair to them. allah does not direct those who deny the truth to the right way.
إنما النسيء زيادة في الكفر يضل به الذين كفروا يحلونه عاما ويحرمونه عاما ليواطئوا عدة ما حرم الله فيحلوا ما حرم الله زين لهم سوء أعمالهم والله لا يهدي القوم الكافرين