The Bodhisatta was once born in the lowest caste, and one day went on a journey, taking his food in a basket. On the way he met a young man from Benares, Satadhamma, a magnifico. They travelled together, and when the time came for the meal, because Satadhamma had no food, the Bodhisatta offered him some. "I could not possibly take yours," said the magnifico, "because you are the lowest of the low." The Bodhisatta ate some of the food and put the rest away. In the evening they bathed, and the Bodhisatta ate without offering Satadhamma anything. The latter had expected to be asked again and was very hungry. But finding that he was offered nothing, he asked the Bodhisatta for some and ate it. As soon as he had finished he was seized with remorse that he should thus have disgraced his family. So greatly was he upset that he vomited the food, and with it some blood. He plunged into the wood and was never heard of again.
The story was related in reference to monks who earned their living in the twenty one unlawful ways, as physicians, messengers, etc. The Buddha summoned them and warned that food unlawfully come by was like red hot iron, a deadly poison. It was like partaking of the leavings of the vilest of mankind. J.ii.82 5.