Musnad Ahmad 25:1037

Yahya ibn Adam narrated to us, Mufaddal narrated to us, from Mansur, from Mujahid, from Tawus, from Ibn Abbas, who said: The Messenger of Allah (peace and blessings of Allah be upon him) said on the day of the conquest of Makkah: "Indeed, this city is sacred; Allah has made it sacred. Killing was not made lawful in it for anyone before me, and it was made lawful for me for an hour of a day. So it is sacred by the sanctity of Allah until the Day of Resurrection. Its game shall not be driven away, its thorny plants shall not be cut, and its lost property shall not be picked up except by one who announces it, and its fresh grass shall not be mowed." Al-Abbas said: "O Messenger of Allah, except for *idhkhir* (lemon grass), for it is for their houses and their blacksmiths." He said: "Except for *idhkhir*." "And there is no *hijrah* (migration) after the conquest, but there is *jihad* and intention. And if you are called to march forth, then march forth."