I wrote the fast back in January 2014 while I was in a very hard place in my life. It is based on Isaiah 58, and Exodus 23:25-26. The song doesn't follow the current musically expected patterns (verse>chorus>verse>chorus>bridge) but challenges those conventions has an pre/post verse pattern, followed by four verses, which are broken up by an instrumental, that serves as a preview of the vocalized outro. 

The song themes charity and justice, and the blessing of living by those virtues. Not a church theme you hear these days. It's a hard song, I think. It's not meant to imply that there is no tribulation when a believer is virtuous (truth is quite contrary to that!) but to reflect on the character of God that delights in these virtues and is at liberty to respond with blessing in the form of fertile works. Some people say there is a “law” of sowing and reaping. It is not a law, for a law is true in all instances. 

Galatian 6:7 (LSV) Do not be led astray: God is not mocked; for what a man may sow - that he will also reap

Jeremiah 12:13 (LSV) They sowed wheat, and have reaped thorns, They have become sick - they do not profit. And they have been ashamed of your increases, Because of the fierceness of the anger of YHWH.

Micah 6:15 (LSV) You sow, and do not reap, You tread the olive, And you do not pour out oil, And new wine - and you do not drink wine. 

Zephaniah 1:13 (LSV) And their wealth has been for a spoil, And their houses for a desolation, And they ahve built houses, and do not inhabit, And they have planted vineyards, And they do not drink their wine.

So here are three instances where people are not reaping what they have sowed. Us Christians don't anyways, because if we reaped the death we sowed by our prior sinful nature, we wouldn't be alive in Christ by the Spirit. 

While these song verses are meant to encourage the believer to live virtuously. Our fast is obedience to YHWH revealed by Jesus Christ and the Spirit of Truth. Whether the reward is today or tomorrow, in the present age, or the age to come, the principles of God are true.