Is it safe to sell iPhone 5 with my SIM card inside?

I just received the iPhone 5 with renewal contract. The new SIM card is inside. I want to leave it sealed to sell at a higher price. Is it safe to sell it like that? Can the buyer activate the phone with the information included on the phone alone?

The SIM has nothing to do with your passwords for whatever services you use. The SIM basically just stores your phone number.It'safe.

This should not be a problem and will help the buyer activate as it is on contract. However, make sure that the buyer does put everything in their name or you might have to pay the charges.