Sayyiduna Abu Hurayrah (may Allah be pleased with him) reported, concerning the Prophet's (peace and blessings be upon him) account of Makkah, that he (peace and blessings be upon him) said: "Its thorns are not to be uprooted, its trees are not to be cut, and its fallen items are not to be picked up, except by one who announces them."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب اللقطة / 12117
It is narrated from Sayyiduna Abdullah bin Abbas (may Allah be pleased with them both) that the Messenger of Allah (peace and blessings be upon him) said on the day of the Conquest of Makkah: "This city is sacred; Allah Almighty has made it sacred. Killing in it was not lawful for anyone before me, and it was made lawful for me only for an hour; so it is sacred. Allah Almighty has made it sacred until the Day of Resurrection. Its game is not to be chased away, its thorns are not to be cut, and its lost property is not to be picked up except by one who announces it, and its trees are not to be uprooted." Sayyiduna Abbas (may Allah be pleased with him) said: Except idhkhir, for it is used in the roofs of houses. He (peace and blessings be upon him) said: "Idhkhir is permitted."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب اللقطة / 12118
It is narrated from Sayyiduna Ibn Abbas (may Allah be pleased with them both) that the Prophet (peace and blessings be upon him) said: "Its grass is not to be cut, its trees are not to be cut, its game is not to be chased away, and picking up its lost property is not lawful except for one who announces it." Sayyiduna Abbas (may Allah be pleased with him) said: O Messenger of Allah! Except idhkhir. He (peace and blessings be upon him) said: "Idhkhir is permitted."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب اللقطة / 12119
Abu Ubayd (may Allah have mercy on him) said: Regarding the hadith, I have nothing other than what Abd al-Rahman bin Mahdi (may Allah have mercy on him) said: that the one who finds it (the lost property) must announce it forever; otherwise it is not lawful for him to touch it.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب اللقطة / 12120
It is narrated from Sayyiduna Abd al-Rahman bin Uthman al-Taymi (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) forbade "picking up the lost property of the pilgrims."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب اللقطة / 12121