Is it safe to buy a brandnew reported stolen/lost iphone 5S from a random seller?

I have been offered to buy a brand new iPhone 5S from a guy. I'm too concerned about the tracking thing. Is it safe?

Are you asking if it is legal to buy stolen merchandise? The answer is definitely no. It is not legal to possess stolen merchandise because the law does not consider that to be legal ownership.

Why would you want to do that use the money and get a legit phone

Why would you buy a phone reported lost/stolen? If it is stolen then you're breaking the law by possessing stolen property. Furthermore, because the phone has been reported to the carrier, it's now blacklisted and can't be activated, so you're buying a useless phone.

If you reset it they can't track it but msybey you should get the info contact the owner may get reward money and buy you one i would pay reward

Is not safe and you can end up either getting the a phone that can't be used at all because if has "Find my phone" turn on and is linked to an apple account so you will never be able to activate it. This is lets say the worst scenario, well beside that when the polices comes looking for the iPhone because was declared stolen.
If was declared lost stolen/lost was probably blacklisted in your country, so will not be able to use it with any network in that country