This consultant the company brought in - it's truly easier to invite him in than to send him away.
Tips
culture
Rooted in folk religion. Inviting a deity to a household altar 请神 is a simple ritual; properly seeing the deity off 送神 so it doesn't linger and cause trouble is much harder. The saying generalizes: hiring someone, taking on a partner, or accepting 'help' is easy; extracting yourself later isn't.
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A 俗语 (common saying), not a formal chengyu. Used to warn against rash entanglements: bad employees, freeloading guests, dodgy investors, problematic in-laws.