Safe will depend on how well the person pays. I would recommend setting up the contracts such that the future renter will loose big if they do not pay on time. If the person does not have cash to put in the deal, I would make you putting six months rent into escrow for the purchase. That way they have some reason to pay on time everytime. But most important keep this on a professional basis not on a to help someone out. If you are doing it to help out.Then just give cash not your credit.