I heard the Prophet ﷺ giving a sermon during the year of the Conquest. He said, "People, Allah made Mecca sacred the day He created the heavens and the earth, so it remains sacred until the Day of Resurrection. Its trees are not to be cut, its game is not to be startled, and its lost property is not to be picked up except by one who will announce it publicly."Abbas said, "Except for idhkhir grass, for it is used in our homes and graves."The Messenger of Allah ﷺ replied, "Except for idhkhir."
حدثنا محمد بن عبد الله بن نمير حدثنا يونس بن بكير حدثنا محمد بن إسحق حدثنا أبان بن صالح عن الحسن بن مسلم بن يناق
سمعت النبي ﷺ يخطب عام الفتح فقال يا أيها الناس إن الله حرم مكة يوم خلق السموات والأرض فهي حرام إلى يوم القيامة لا يعضد شجرها ولا ينفر صيدها ولا يأخذ لقطتها إلا منشد فقال العباس إلا الإذخر فإنه للبيوت والقبور فقال رسول الله ﷺ إلا الإذخر
[Its chain is hasan] Bukhari narrated it in Tarikh al-Kabir 1/451 from the hadith of Yunus bin Bukayr, in abridged form, and he cited it without a full chain in his Sahih (1349, Funerals, chapter on idhkhir grass and hashish in the grave). Aban was deemed reliable by the majority, which is the correct view, and his hadith has very many corroborating reports.