Mbh 13.143.2b

That man who has attained to clearness of vision through practice of the duties of his own order, who is endued with knowledge and science, who is pure (in body and mind), who is conversant with every duty and devoted to the practice of all his duties, is sure to enjoy the rewards of righteousness. I shall now recite to thee, O goddess, a saying uttered by Brahma (the Self-born) on this subject. Those that are righteous and desirous of acquiring merit always pursue with firmness the culture of the soul. The food that comes from cruel and fierce persons is censurable. So also is the food that has been cooked for serving a large number of persons. The same is said of the food that is cooked in view of the first Sraddha of a deceased person. So also is the food that is stained in consequence of the usual faults and the food that is supplied by a Sudra. These should never be taken by a Brahmana at any time[570]. The food of a Sudra, O goddess, is always disapproved of by the high-souled deities. Even this, I think, is the authority enunciated by the Grandsire with his own mouth. If a Brahmana, who has set up the sacred fire and who performs sacrifices, were to die with any portion of a Sudra's food remaining undigested in his stomach, he is sure to take birth in his next life as a Sudra. In consequence of those remains of a Sudra's food in his stomach, he falls away from the status of a Brahmana. Such a Brahmana becomes invested with the status of a Sudra. There is no doubt in this. This Brahmana in his next life becomes invested with the status of that order upon whose food he subsists through life or with the undigested portion of whose food in his stomach he breathes his last.[571] That man who, having attained to the auspicious status of a Brahmana which is so difficult to acquire, disregards it and eats interdicted food, falls away from his high status.