Where does the phrase "everywhere in life is similar, it should be like a flying dragon stepping on snow and mud" come from?

From Su Shi's "Hezi Nostalgia from Mianchi".

Original text of the work:

"He Zi Nostalgic from Mianchi"

Everywhere in life is similar, it should be like a flying dragon stepping on slush.

Occasionally, there are fingers and claws left on the mud, and Hongfei is counting the things.

The old monk has died and a new pagoda has been built. There is no reason to see the old inscriptions if the walls are broken.

Do you still remember the rough days? The road was long, people were trapped and the donkeys brayed.

About the author:

Su Shi (1037-1101), a writer, calligrapher, painter and gourmet in the Northern Song Dynasty. His courtesy name is Zizhan and his nickname is Dongpo Jushi. Han nationality, Sichuan native, buried in Yingchang (now Jiaxian County, Pingdingshan City, Henan Province). He had a bumpy official career throughout his life, but he was knowledgeable and talented. He was excellent in poetry, calligraphy and painting. His writing is unbridled, clear and fluent. Together with Ouyang Xiu, he is called Ou Su, and he is one of the "Eight Great Masters of the Tang and Song Dynasties". His poetry is fresh and vigorous, good at using exaggeration and metaphor, and his artistic expression is unique. He is also called Su Huang together with Huang Tingjian. He started a bold and unrestrained school and had a huge influence on later generations. Together with Xin Qiji, he was called Su Xin. He was good at calligraphy in running script and regular script. He could create his own ideas. His pen was rich and ups and downs, and he had an innocent taste. He was called Song Dynasty together with Huang Tingjian, Mi Fu and Cai Xiang. The four schools have the same painting studies and literature, advocate spiritual similarity in painting, and advocate "scholar painting". He is the author of "The Complete Works of Su Dongpo" and "Su Dongpo Yuefu".