Following are a number of back-translations as well as a sample translation for translators of Isaiah 51:2:

• Kupsabiny: “Think about your ancestor/grandfather Abraham
  and your grandmother Sarah who bore you.
  Abraham had no child when I called him,
  but I blessed him and gave him many grandchildren/descendants.” (Source: Kupsabiny Back Translation)
• Newari: “Look at your ancestor Abraham
  and [at] Sarah, who gave birth to your whole nation.
  When I called, Abraham was only one [person],
  then I blessed him and caused him to be many.” (Source: Newari Back Translation)
• Hiligaynon: “The LORD said, ‘[You (plur.)] listen to me, you (plur.) who want to-be-saved and take-refuge on me. You (plur.) remember Abraham and Sara your (plur.) ancestors/forefathers. They are like a rock from where you (plur.) were-chipped-from or a hole/break-through where you (plur.) have-been-digged. When I called Abraham he was alone, but I blessed him and have-given (him) many descendants.” (Source: Hiligaynon Back Translation)