Overall meaning : The Almighty states that the number of months with Him, Exalted be He, is twelve months, as determined and decreed by Him and recorded on the Preserved Tablet since the creation of the heavens and the earth. Of these, four during which fighting is forbidden and sins committed in them are considered even graver than in other months. That is the right religion and the accurate reckoning, so do not wrong yourselves in them by committing evil deeds; and fight the idolaters who associate partners with Allah all together just as they fight you all together, and know that Allah is with the righteous who do what He commands and avoid what He forbids.
Allah Almighty explains that the Quraysh idolaters were in the habit of delaying the sacred months and changing the times He has set for them, an act which only increased in their unbelief. Whenever it suited them, they would declare the sacred lunar month of Muharram ordinary and replace it with the ordinary month of Safar, which they then declared sacred. In this way, they made the month of Safar acquire the sacredness of the month of Muharram for which they had substituted it. In the following year, they would declare the month of Muharram sacred again, whereby the unbelievers were led astray. They considered such postponement and change lawful one year and unlawful another year to tally exactly with the number of months Allah has made sacred every year. By doing so they made lawful what Allah has forbidden. Their evil deeds seemed pleasing to them. Allah does not guide those who persist in their unbelief.