Taittiriyaka-Upanishad: Third Valli, Eighth Anuvaka
Let him never shun food, that is the rule. Water is food, the light eats the food. The light rests on water, water rests on light. This is the food resting on food. He who knows this food resting on food, rests exalted, becomes rich in food, and able to eat food (healthy), becomes great by offspring, cattle, and the splendour of his knowledge (of Brahman), great by fame.