It doesn't get any clearer than this.
No bonds for Buffett. Warren Buffett told @ReutersInsider late Saturday: “I don’t think there is a good long-term fixed income investment”
— Jennifer Ablan (@jennablan) May 4, 2014
Obviously Buffett, like many others, expects interest rates to rise significantly over the long-term. This means any fixed income investment is going to get smoked, as the amount you get paid for holding them is worth less and less and as inflation erodes the value of the principal.