誓言是蛊惑人心的最大毒药
[shì yán shì gŭ huò rén xīn de zuì dà dú yào]
Translates as 'Oaths are the strongest poison that can bewitch hearts'. It's a metaphor expressing deep cynicism towards promises, suggesting that vows and pledges often mislead and cause great harm rather than representing truth and commitment.