What if a guy buys cash from me and block me from...

We would like to inform you that you can file a complaint before the UAE judiciary and the public prosecution against by stating the details of the complaint with the need to mention the names you dealt with and details of the person who dealt with him and the need to include in the complaint list the names of people who know the details of the incident to request their testimony and must be requested through the list to recover your money by the perpetrator.

*** As to the legal rooting of your case, it is a crime of fraud in accordance with the provisions of the UAE Penal Code and its penalty is imprisonment and a fine based on the text of Article 399, which stipulates:

Article 399:

Detention or a fine shall be imposed upon any one who seizes, for himself or for another, a movable property, or obtains a document or signature thereon, cancellation or destruction thereof or amendment thereto by fraudulent means, or by assuming a false name or capacity, where such an act leads to deception of a victim and leads him to surrender. The same punishment shall apply to anyone who disposes of real estate or movable property knowing that such a property is not owned by him or that he has no right to dispose thereof, or if he disposes of a thing knowing that it has been previously disposed of or contracted upon, provided that such acts cause damage to a third party.