the idea behind it
The color green has a special place in Islam. It is used in the decoration of mosques, the bindings of Qur'ans, the silken covers for the graves of Sufi saints, and in the flags of various Muslim countries. Green has been associated with Islam for many centuries. It is not clear why this is so. Some say green was Muhammad’s favorite color and that he wore a green cloak and turban. Others believe that it symbolizes nature and life, hence the physical manifestation of God. In the Qur'an it is said that the inhabitants of paradise will wear green garments of fine silk. While the reference to the Qur'an is verifiable, it is not clear if other explanations are reliable or mere folklore. Regardless of its origins, the color green has been considered especially Islamic for centuries.Crusaders avoided using any green in their coats of arms, so that they could not possibly be mistaken for their Muslim opponents in the heat of battle.