Digha Nikaya 2:41
SUJATOSeyyathāpi, bhikkhave, ubhatomukhā putoḷi pūrā nānāvihitassa dhaññassa, seyyathidaṁ—sālīnaṁ vīhīnaṁ muggānaṁ māsānaṁ tilānaṁ taṇḍulānaṁ. Tamenaṁ cakkhumā puriso muñcitvā paccavekkheyya: ‘ime sālī, ime vīhī ime muggā ime māsā ime tilā ime taṇḍulā’ti.
It’s as if there were a bag with openings at both ends, filled with various kinds of grains, such as fine rice, wheat, mung beans, peas, sesame, and ordinary rice. And a person with clear eyes were to open it and examine the contents: ‘These grains are fine rice, these are wheat, these are mung beans, these are peas, these are sesame, and these are ordinary rice.’