Verses 1-7 If we truly desire to know the will of God in doubtful matters, we must not only consult his word and ministers, but seek his direction by fervent prayer. Those who would know God's mind should consult God's ministers; and, in doubtful cases, ask advice of those whose special business it is to search the Scriptures. The Jews seemed to question whether they ought to continue their fasts, seeing that the city and temple were likely to be finished. The first answer to their inquiry is a sharp reproof of hypocrisy. These fasts were not acceptable to God, unless observed in a better manner, and to better purpose. There was the form of duty, but no life, or soul, or power in it. Holy exercises are to be done to God, looking to his word as our rule, and his glory as our end, seeking to please him and obtain his favour; but self was the centre of all their actions. And it was not enough to weep on fast days; they should have searched the Scriptures of the prophets, that they might have seen what was the ground of God's controversy with their fathers. Whether people are in prosperity or adversity, they must be called upon to leave their sins, and to do their duty.
Verses 8-14 God's judgements upon Israel of old for their sins, were written to warn Christians. The duties required are, not keeping fasts and offering sacrifices, but doing justly and loving mercy, which tend to the public welfare and peace. The law of God lays restraint upon the heart. But they filled their minds with prejudices against the word of God. Nothing is harder than the heart of a presumptuous sinner. See the fatal consequences of this to their fathers. Great sins against the Lord of hosts, bring great wrath from his power, which cannot be resisted. Sin, if regarded in the heart, will certainly spoil the success of prayer. The Lord always hears the cry of the broken-hearted penitent; yet all who die impenitent and unbelieving, will find no remedy or refuge from miseries which while here they despised and defied, but which they then will not be able to bear.