a virtuous person does not compromise their principles even in hardship
A yojijukugo (four-character idiom) expressing the idea that one should not commit a dishonorable act, no matter how desperate the circumstances. Rare in modern conversation; mainly encountered in literary or classical contexts.
The phrase 'akuboku tōsen' expresses the mindset of a noble person who does not stray from the path even when in dire straits.