Mencius - Book 6, Part 2, Chapter 14

The disciple Ch'an said, 'What were the principles on which superior men of old took office?' Mencius replied, 'There were three cases in which they accepted office, and three in which they left it.

'If received with the utmost respect and all polite observances, and they could say to themselves that the prince would carry their words into practice, then they took office with him. Afterwards, although there might be no remission in the polite demeanor of the prince, if their words were not carried into practice, they would leave him.

'The second case was that in which, though the prince could not be expected at once to carry their words into practice, yet being received by him with the utmost respect, they took office with him. But afterwords, if there was a remission in his polite demeanor, they would leave him.

'The last case was that of the superior man who had nothing to eat, either morning or evening, and was so famished that he could not move out of his door. If the prince, on hearing of his state, said, "I must fail in the great point, that of carrying his doctrines into practice, neither am I able to follow his words, but I am ashamed to allow him to die of want in my country;" the assistance offered in such a case might be received, but not beyond what was sufficient to avert death.'

~ James Legge translation via nothingistic.org ~

 Go here to read the introductory post to this serialized version of the Works of Mencius.