Rabbi Ahai ben Yoshiya says: One who purchases grain in the market—to what may such a person be likened? To an infant whose mother died, and they pass him from door to door among wet nurses and the baby is not satisfied. One who buys bread in the marketplace—to what may such a person be likened?  It is as if he is dead and buried. But one who eats from his own is like an infant raised at his mother’s breasts. 

He used to say: During the time that a person eats from what he has grown himself—his mind is tranquil. Even one who eats from that which his father has grown or from that of his mother’s or son’s, his mind is not tranquil—and you do not [even] need to say [food grown] from that of others [non-relatives].