This salawikain means that wherever we go, we should always be cautious as there will always be someone that might betray or double-cross us.
Parents/elders would use this proverb to advise a person (usually in the younger generations) who is about to go into a journey. This is a useful reminder to those going abroad or migrating to another country – that, however friendly the place (where they are going) maybe, they should remain vigilant as there is always the danger of getting betrayed.
Reference: http://www.pinoystop.org/salawikain-lahat-ng-gubat-ay-may-ahas/
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