In economic theory, risk aversion is represented by a negative second derivative of the utility function, while prudence (often associated with precautionary saving) is defined by a positive third derivative.
The claim states a standard microeconomic definition regarding higher-order risk preferences established by Kimball (1990), where prudence corresponds to a positive third derivative of the utility function ($u''' > 0$). Because this is a standard textbook definition in economics, it is common knowledge by definition and does not require citation of specific retrieved empirical papers.