Following are a number of back-translations as well as a sample translation for translators of Isaiah 56:3:

• Kupsabiny: “The foreigner who worships God should not say
  ‘God will separate me from where his people are.’
  The castrated man should not say,
  ‘I am a just a dried up tree.’” (Source: Kupsabiny Back Translation)
• Newari: “Do not let any foreigner who has committed himself [lit.: who has given himself by promise] to the LORD speak like this —
  "Certainly the LORD has kept me separate from his own people."
  Don’t let any eunuch speak like this — "I am like a dried-up tree."” (Source: Newari Back Translation)
• Hiligaynon: “The non Israelinhon who have-handed-over their lives to the LORD should not think that they will- never -be-joined by the LORD with his people. And the people who have-been-castrated should not also think that because they can- not -give-birth they cannot become part of the people of God.” (Source: Hiligaynon Back Translation)
• English: “And foreigners who have believed in me should not say,
  ‘Yahweh will surely not allow me to belong to his people.’
  And eunuchs should not say,
  ‘Because I am unable to have children, I cannot belong to Yahweh;
  I am like a tree that has completely withered.’” (Source: Translation for Translators)