What two lines did Du Fu use to express his views on the war?

There is a limit to killing people, and all countries have national boundaries. If you can invade the mausoleum, how can you kill more? "The poet declaimed, expressed his feelings, and made a loud voice. In his view, keeping Qiang Bing is only for guarding the border, not for fighting. Whether "shooting horses" for the enemy, "killing people" for necessity, or "capturing the king" for Qiang Bing, it should be limited to "controlling the invasion of the mausoleum", not to mention arrogantly invading foreign countries. This idea of fighting with war and stopping aggression with Qiang Bing is a grand theory and a good strategy to ensure border security; It reflects the interests of the country and the wishes of the people.