Many do not realize that we are here in this world to perish; those who do realize this still their quarrels at once.

The Buddha attaches the practice of non-hatred to one observable fact: we are mortal. The argument is unsentimental. People who do not see that they are dying have time for hatred. People who see it directly do not. There is no metaphysics here, only a frame correction. The verse is not asking for piety. It is asking for accurate perception of the timeframe. Once that perception sharpens, the smaller quarrels fall away of their own weight.