How do I convince my dad to invest his money in some way?

My dad is an attorney, and is about 60. He has about 700k in cash, owns a 500k house, currently makes about 200k a year, and will receive a pension of about 100k a year upon retirement. All of his money is currently in the bank, and is only making pennies a year. What is a conservative method I can mention to him, that would not expose him to too much risk. Technically he could live as he currently does, without ever touching the principle, on his pension alone. I would say buying bonds sound like a good idea for him, with possibly a bit in mutual funds. Currently all my money is in a variety of Stocks, that yield 10-20% a year, but he is not interested in doing that, and thinks it takes too much time to get involved in the stock market. I try to tell him it doesn't, and that there are very conservative ways of making money, that beats inflation, and doesn't expose you to very much risk. How should I approach him? What are some investment techniques that I could recommend to him?