The writing of knowledge

Narrated Abu Huraira: In the year of the Conquest of Mecca, the tribe of Khuza`a killed a man from the tribe of Bani Laith in revenge for a killed person, belonging to them. They informed the Prophet (sallallahu 'alaihi wa sallam) about it. So he rode his Rahila (she-camel for riding) and addressed the people saying, "Allah held back the killing from Mecca. (The sub-narrator is in doubt whether the Prophet (sallallahu 'alaihi wa sallam) said "elephant or killing," as the Arabic words standing for these words have great similarity in shape), but He (Allah) let His Apostle and the believers over power the infidels of Mecca. Beware! (Mecca is a sanctuary) Verily! Fighting in Mecca was not permitted for anyone before me nor will it be permitted for anyone after me. It (war) in it was made legal for me for few hours or so on that day. No doubt it is at this moment a sanctuary, it is not allowed to uproot its thorny shrubs or to uproot its trees or to pick up its Luqat (fallen things) except by a person who will look for its owner (announce it publicly). And if somebody is killed, then his closest relative has the right to choose one of the two-- the blood money (Diyya) or retaliation having the killer killed. In the meantime a man from Yemen came and said, "O Allah's Messenger (sallallahu 'alaihi wa sallam)! Get that written for me." The Prophet (sallallahu 'alaihi wa sallam) ordered his companions to write that for him. Then a man from Quraish said, "Except Al-Idhkhir (a type of grass that has good smell) O Allah's Messenger (sallallahu 'alaihi wa sallam), as we use it in our houses and graves." The Prophet (sallallahu 'alaihi wa sallam) said, "Except Al-Idhkhir i.e. Al-Idhkhir is allowed to be plucked."