When Bu Buqi, a follower of Confucius, became premier of Shanfu, the Sage sent Wu Mashi to observe him and report back to Confucius on how his pupil was doing in governing the land. After Wu entered the territory of Shanfu, he saw that the people there returned young or pregnant fish that they had caught to the water without being compelled to. Obviously, Confucius had been a successful teacher.
孔子弟子宓不齊任單父宰相，做老師的不免關心學生的政績，就派巫馬師去觀察，巫馬師進入單父地界後，發現當地的漁民主動把捕到的幼魚和懷妊之魚放回水裡，顯然孔夫子教導有方！