He who gives food, gives longevity, pleasant complexion, happiness, stamina and intelligence

--- Gotama Buddha, Bhojana Sutta, Panchaka Nipata, The Fives,  Anguttara Nikaya, cited in the liturgy (pdf) of Hunger No More: An Interfaith Convocation of Prayer and Commitment, June 5, 2005, Washington National Cathedral.

Quote as cited:

Monks, he who gives food, gives longevity, pleasant complexion, happiness,
stamina and intelligence.

The liturgy (pdf) includes a long list of "National Religious Leadership Statements on Hunger and Poverty," including this by Bhante M. Dhammasiri, President, Buddhist Vihara, Washington, DC:

Buddhism advocates generosity as one of the main virtues accumulated even by the potential
Buddha. Feeding poor people is one of the duties of a Buddhist. One who is capable of earning
more with ethical means shares his/her surplus with others. Food, clothing, shelter and medicine are four essentials that a person needs. Buddhism emphasizes the fact that everybody lives on food and that is the main requisite. The Buddhist generosity is culminated when one sacrifices his/her own life for the benefit of others. According to Buddhism, before asking the person to follow the teachings of the Buddha, one should check whether the person had enough to eat because the hungry cannot comprehend the essence of the teachings. The Buddha mentioned that hunger is the worst disease.

One possible source of the reference to not being hungry before receiving teaching may be the story cited in  Eat To Live, Not Live To Eat, in which the Buddha ensured that a poor man had been fed before starting his teaching, keeping many others waiting in the process.