He found an amount of cash in the Haram (in Makkah)

The scholars differed with regard to lost property found
in the Haram: is it like lost property found elsewhere, which the finder may keep after
announcing it and looking for its owner for one year, or can it never become the property
of another? Some scholars said that the finder can keep it because of the general meaning
of the hadeeth; others said that he cannot keep it, and the search to identify the owner
should continue indefinitely, because the Prophet
(peace and blessings of Allaah be upon
him) said concerning Makkah, “It is not permissible for anyone to keep lost property
found there except the one who claims it by identifying it properly.” Shaykh al-Islam
Ibn Taymiyah (may Allaah have mercy on him) favoured the latter opinion, and said:
“He should not keep it at all, because that is forbidden, and it should be announced
indefinitely in a search to identify the owner.” This is the apparent meaning of the
report which says it is forbidden.

Al-Mulakhkhas al-Fiqhi by Saaalih al-Fawzaan, 150.

For more information, please see Question
# 5049

Shaykh Ibn ‘Uthaymeen was asked the following question: is it
permissible for me to pick up lost property in Makkah and take it and announce it in the
area where I live, or do I have to announce it at the doors of the mosque and
market-places etc. in Makkah itself?

He answered, may Allâh preserve him: the case of lost property in
Makkah is unique in that it is not permissible for anyone to pick it up except the one who
wants to announce it indefinitely or hand it over to those who are in charge of such
things, because the Prophet
(peace and blessings of Allaah be upon him) said, “It is
not permissible to pick up lost property except for the one who wants to announce
it.” The reason behind this is that if the lost property is left where it is, its
owner will probably come back and find it. On this basis, we say to this brother: you have
to announce it in Makkah, in and around the place where you found it, such as at the doors
of the mosque and in places where people gather, otherwise you should hand it in to those
whose job it is to take care of lost property etc. Fatawa Islamiyah, 2/311.

And Allâh knows best.