隔舍须有耳，窗外岂无人 — “Even in seemingly private settings”

隔舍须有耳，窗外岂无人 is a Chinese idiom (chengyu) meaning “Even in seemingly private settings”. One must be cautious about what they say, as there might always be someone listening or overhearing. It implies that secrets are hard to keep and advises prudence in speech. (Similar to 'Walls have ears.'). Literally, “Next door must have ears; how could there be no one outside the window?”.