Following are a number of back-translations as well as a sample translation for translators of Isaiah 56:6:

• Kupsabiny: “This is what God is saying to
  the foreigners who worship him,
  those who love him and serve him
  those who keep the day of Sabbath obeying it
  and take good care of my covenant.” (Source: Kupsabiny Back Translation)
• Newari: “And foreigners who bind themselves to the LORD, to serve him,
  to love the name of the LORD,
  and to worship him,
  always to honor the Sabbath day,
  and who faithfully keep the covenant
  between me and my people.” (Source: Newari Back Translation)
• Hiligaynon: “‘I will- also -bless the non Israelinhon who handed-over their lives to me in-order to serve me, love, and worship, and they obey what I have-[them]do in the Day For-Resting and obey my covenant.” (Source: Hiligaynon Back Translation)
• English: “I will also bless those who are not Israelis,
  who join themselves to/believe in me,
  and who serve me and worship and love me,
  and who obey my laws about the Sabbath,
  and who faithfully obey all the other laws of the agreement that I made with the Israeli people.” (Source: Translation for Translators)