Phrase built from 《
荀子·
法行》
坚强而不屈,
义也 ('to be firm and unyielding is righteousness') and the description of Han official Wang Gong in 《
后汉书·
王龚传》 as having
坚贞之操 — a steadfast character. Heavily used in 20th-century Chinese political writing for revolutionary martyrs.