Verily, the number of months with Allah is twelve months (in a year) according to the law of Allah since the day He created the heavens and the earth. Among these, four (months) are sacred (Muharram, Rajab, Dhul-Qa’dah and Dhul-Hijjah). That is the established law. Do not do injustice to yourselves (by waging wars) during these (sacred months). And fight the polytheists all together (in your defence) just as they fight you all together. And know that Allah is indeed with those who are God conscious. (9:36)

Commentary
NUMBER 12: At first glance, it may seem strange that Allah is just telling people that there are twelve months in the calendar year, however without a doubt, there is wisdom and a deeper meaning to this verse.
Although Muslims tend to use numbers, perhaps hoping to attract benefit, such as having a phone number or a license plate with the number 786 in it, we do not believe in numerology and we do not attribute special powers to numbers. However, some numbers do occur more frequently in the Islamic teachings than others – such as 40 and 12. In fact, the Quran shows us that there are: 12 months in the year, the Tribes of Israel (Banī Isrāʾīl) were 12 in number; the number of springs which gushed out for them as mentioned in Sūrah al-Baqarah was 12; and the number of Imāms after Prophet Muḥammad are also 12.
In any case, this verse shows us that the order of the world is such that 12 months exist, and for the Muslims, Allah has ordained that four of these are ‘sacred’ – ,– and initiating a war or fighting during these months is not permissible – except in matters of self-defence. 
At one level, this shows us that Islam is not a religion of war, and in actually it puts in place OFFICIAL guidelines and times of a cease-fire which are religiously mandated, and must be upheld with the goal that in that off-time, negotiations and peace treaties can be enacted.
A glance at the wars which have plagued history show us that in the 20th century alone, over 108 million people have been killed – and it continues today in countries like Central and South America, Yemen, Afghanistan, Iraq, Syria and many other places.
May Allah give us all the wisdom to realize and amend our foolish ways, and may He give the oppressors the will to cease and desist their aggressive nature, and if they cannot be persuaded to give up their evil ways, then may they be brought to justice in this world and in the world to come.

Point of Reflection
In Islam there are many ‘sacred’ signs. In this faith, there is a place of safety which is the city of Mecca; there is the inviolable house of Allah in Masjid al-Ḥarām; there are four sacred months; and even a sacred day – Friday – all of which and more must be respected.
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Quran audio files courtesy of: http://everyayah.com 
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