不当人子

Explanation: The words of apology or thanks, meaning is a sin, do not deserve it. 　　Source: Ming Feng Meng, "Awaken the common saying" Thank ten thick volumes the situation, but without power by Paul, improper Son of man, old man transferred, will be paid when the Bong. " 　　Examples: We are fireworks neighbors, hear of this event, the rationale for the service. But also costly old master, ~. (Qing Wu Jingzi "Scholars" Twenty-back)