Following are a number of back-translations as well as a sample translation for translators of Proverbs 26:25:

• Kupsabiny: “Although a black stomached person may try to hide it inside,
  it will be revealed where there are many people (in public).
  His word may seem to be good,
  but do not believe (him), because (he) is envious to finish (it) (full of envy).” (Source: Kupsabiny Back Translation)
• Newari: “Do not believe the tasty words of such people.
  for their hearts are full of seven evil thoughts.” (Source: Newari Back Translation)
• Hiligaynon: “Even-though when he speaks is- convincing, [you (sing.)] do- not -believe him, for what he thinks/thoughts are purely detestable.” (Source: Hiligaynon Back Translation)
• Kankanaey: “It’s as-if it’s nice to listen-to, but do not (sing.) be-trusting, because his bad motives are not countable.” (Source: Kankanaey Back Translation)
• English: “When they say nice things, do not believe them,
  because in their inner beings are many things that Yahweh hates.” (Source: Translation for Translators)