Following are a number of back-translations as well as a sample translation for translators of Isaiah 58:3:

• Kupsabiny: “You are asking, ‘Have we not been fasting, and have you not seen it?
  Why are we humbling ourselves and you do not see it?’
  Look, you are fasting while concentrating on your own matters only
  and you oppress your workers.” (Source: Kupsabiny Back Translation)
• Newari: “They say, ‘We have fasted, why didn’t you see it?
  We humbled [ourselves], why were you not concerned about the matter?’
  "For on the day that you fasted you were only fulfilling your own desires,
  and you were oppressing all your workmen.” (Source: Newari Back Translation)
• Hiligaynon: “They still say to me, ‘We (incl.) have-fasted, but you (sing.) just have- not -paid-attention (to-it). We (incl.) have-done-penance but you (sing.) have- not -noticed it.’
  ‘This is my answer: The truth is, while you (plur.) are-fasting, you (plur.) are- only -thinking of your (plur.) own happiness; and you (plur.) even oppress your (plur.) workers.” (Source: Hiligaynon Back Translation)
• English: “They say, ‘We have fasted/abstained from eating food to please you,
  but you did not notice our doing that.
  We humbled ourselves,
  but you did not pay any attention!’
  I will tell you why I did not pay attention.
  It is because when you fast,
  you do it only to please yourselves,
  and you act cruelly toward all your workers.” (Source: Translation for Translators)