Bù dǎtīng tóngháng de yǐnsī shì zhè yī háng de hángguī.
Not prying into colleagues' private affairs is a rule of the profession.
Tips
mistakes
Read 行 as háng ("trade, profession"), not xíng ("to walk; OK"). 行规 are the unwritten rules each trade enforces among its own — historically codified by guilds (行会), today persisting as professional etiquette.