You don't have to stab someone, but there must be a thorn. We are all passers-by, always in a hurry. In this life, we have to see a lot of scenery and meet all kinds of people. Therefore, we need kindness, but our kindness should also be sharp.
There are good people and bad people in this world. In the world, it is difficult for us to distinguish between people's hearts. Indeed, we have to go through a lot to learn to grow. We don't have to stab people, but there must be thorns. We can be harmless to the world, but we need to protect ourselves. Therefore, everyone should constantly achieve their strongest self, let themselves grow and learn, and thus give themselves a protective layer.
Finally, I want to say that the most elusive heart in the world. So, please leave your kindness to those who really deserve it.