In this world there is nothing that is dearer to a creature than his life. Hence, one should show mercy to the lives of others as he does to his own life.
न हि प्राणात् प्रियतरं लोके किंचन विद्यते। तस्माद् दयां नरः कुर्याद् यथाऽऽत्मनि तथा परे॥