Allah made it sacred

“There is no hijra, but only jihad and intention ; and when you are called to battle, go forth.’’ He also said on the day of the conquest of Mecca, “Allah made this town sacred on the day He created the heavens and the earth, so it is sacred by the sacredness conferred on it by Allah till the day of resurrection. Fighting in it has not been lawful to anyone before me and it has been made lawful for me only during one hour on one day, so it is sacred by the sacredness conferred on it by Allah till the day of resurrection. Its thorns are not to be cut, its game is not to be molested, things dropped are to be picked up only by one who publicly announces it, and its fresh herbage is not to be cut.” Ibn ‘Abbas made the suggestion, “Except the rush, the Messenger of Allah, for it is useful for their blacksmiths and for their houses.” He then said, “Except the rush.” (Bukhari and Muslim.) A version by Abu Huraira has, “Its trees are not to be lopped, and only one who announces it may pick up anything which falls in it.”