因为马善被人骑所以人善被人欺
[yīn wéi mă shàn bèi rén qí suŏ yĭ rén shàn bèi rén qī]
Since a gentle horse can be easily ridden, a kindhearted person is often taken advantage of conveys the wisdom that kindness or goodness without strength or protection can result in exploitation or mistreatment by others.