Han Yu, courtesy name Tuizhi, hailed from Heyang, Henan (present-day Meng County, Henan), and was a renowned Tang Dynasty writer and philosopher. After passing the imperial exams, he served as a censor but was later demoted to magistrate of Shanyang County. At thirty-five, he became a professor at the Imperial Academy in the capital, and later Vice Minister of Justice. Once, he submitted a memorial to Emperor Xianzong that nearly cost him his head.
At the time, Buddhism was so widespread that from officials to commoners, many believed in it, even Emperor Xianzong himself was a devout follower. Once, Xianzong brought a relic said to be a bone of the Buddha Sakyamuni into the palace for worship. Han Yu opposed this act and wrote a memorial titled "On the Buddha Bone Table" to dissuade the emperor. In it, Han Yu stated: "Your Majesty, this is nothing but a filthy relic of a long-dead barbarian. It should not be brought into the palace, for it will only mislead the people and corrupt our traditions."
Buddhism was introduced from abroad; ancient China had none. Sage rulers like Yao, Shun, and Yu knew nothing of Buddhism, yet they governed well, enjoyed long reigns, and lived to old age. Buddhism entered China during Emperor Ming of the Eastern Han Dynasty, who ruled only eighteen years. Later dynasties like Song, Qi, Liang, Chen, and the Northern Wei fervently embraced Buddhism, yet their reigns were short. Consider Emperor Wu of Liang: he abstained from meat and animal sacrifice in worship, even becoming a monk three times, yet he was besieged by rebels and starved to death. He sought Buddha's protection but met a tragic end.
Now, Your Majesty has welcomed the Buddha's relic into the palace for worship, prompting nobles and ministers to rush about making offerings and wasting vast wealth. Some ignorant commoners, driven to madness, even burn their own bodies to show devotion to the Buddha. This corrupts public morals and will be spread as a laughingstock far and wide—this is no trivial matter! In my view, that relic should be thrown into water or cast into fire!
Emperor Xianzong read the memorial and believed Han Yu was implying that the emperor himself would not live long, for which he wanted to have Han Yu beheaded. Thanks to Prime Minister Pei Du pleading on Han Yu's behalf, the punishment was reduced to demoting him to serve as the prefect of Chaozhou.
Later, the idiom "Shang Feng Bai Su" came to describe corrupting social morals, often used to condemn improper behavior.
Source: *Old Book of Tang*, "Biography of Han Yu"
Meaning of the Idiom: Later, the Chinese idiom "伤风败俗" came to describe corrupting social morals, often used to condemn improper behavior.