Isaiah 58:6,7

Description of the true fast in which Jehovah delights. The duties enjoined fall under two heads: (1) abstinence from every form of oppression (Isaiah 58:6), and (2) the exercise of positive beneficence towards the destitute (Isaiah 58:7). In naming these things as the moral essence of fasting, the prophet may be guided by the principle so often inculcated by our Lord, that he who would obtain mercy from God must shew a merciful disposition towards his fellow-men (Matthew 5:7; Matthew 6:12; Matthew 18:35 &c.). Or the idea may be that the spirit of self-denial possesses no value before God unless it be carried into the sphere of social duty.

the bands(R.V. bonds) of wickedness i.e. unjust and oppressive obligations.

to undo the heavy burdens Lit. to untie the Bands of the yoke.

the oppressedis literally the "broken" (Deuteronomy 28:33; ch. Isaiah 42:3), bankrupts, whose liberty had been forfeited to their creditors (cf. Nehemiah 5:5).