When Buddha himself was asked to summarize his teaching, he said,

Commit not a single unwholesome action,
Cultivate a wealth of virtue,
To tame this mind of ours,
This is the teaching of all the buddhas.

认清世间一切现象都是无常的事实，就能完成内心世界的真正平安。

 by 圣严法师

When sitting in meditation, say, “That’s not my business!” with every thought that comes by.

by Ajahn Chah

When the days become longer and there is more sunshine, the grass becomes fresh and, consequently, we feel very happy. On the other hand, in autumn, one leaf falls down and another leaf falls down. The beautiful plants become as if dead and we do not feel very happy. Why?

I think it is because deep down our human nature likes construction, and does not like destruction. Naturally, every action which is destructive is against human nature. Constructiveness is the human way. Therefore, I think that in terms of basic human feeling, violence is not good. Non-violence is the only way.

by Dalai Lama