Isaiah 58:3

Wherefore have we fasted, say they, and thou seest not?
&c.] Our fasting; takest no notice of it; expresses no approbation of it, and pleasure in it: this is put for all religious services, being what was frequently performed under the Old Testament, not only at certain times appointed by the Lord, but on other occasions, and of their own fixing; in which they put their confidence, and often boasted of, ( Luke 18:12 ) : "wherefore have we afflicted our soul", by fasting, "and thou takest no knowledge?" of that, nor of us, and dost not save us from our enemies, and deliver us from our troubles, and bestow favours on us: they had a high opinion of their own performances, and thought that God must have likewise; and were displeased that he showed no more regard unto them: behold, in the day of your fast you find pleasure;
this, and what follows in the two next verses, are an answer to their questions, and give reasons why the Lord took no more notice of their fasting, or of their services; because they were not done aright, they found their own pleasure in them; not that they indulged to bodily recreations and carnal delights, but they gratified the inward desires of the flesh, malice, envy, and the like; and they pleased themselves with their own duties, and fancied they procured the favour of God by them: and exact all your labours;
of their servants, or their money of their debtors; they grieved and afflicted their debtors, by demanding their debts of them, as Jarchi interprets it; and that in a very rigorous manner, requiring whole and immediate payment; or, as it is usual with establishments, they require an exact conformity to their manner of service, worship, and discipline.