Tao Te Ching · Ch. 43

天下之至柔,馳騁天下之至堅。無有入無間,吾是以知無為之有益。不言之教,無為之益,天下希及之。

Tiān xià zhī zhì róu, chí chěng tiān xià zhī zhì jiān. Wú yǒu rù wú jiān, wú shì yǐ zhī wú wéi zhī yǒu yì. Bù yán zhī jiào, wú wéi zhī yì, tiān xià xī jí zhī.

The softest thing in the world overpowers the hardest. What has no substance enters where there is no space. From this I know the value of non-action. Teaching without words and the benefit of non-action — few in the world attain these.

— Tao Te Ching 43

Source: Wang Bi edition (Chinese) + Hanyu Pinyin transliteration