Adam Clarke on Isaiah 58:14

Then shalt thou delight thyself - If all fasts and religious observances be carried on in the spirit and manner recommended above, God's blessing will attend every ordinance. But in public fasts, prescribed not in the Book of God, but by the rulers of nations in general (very unfit persons) care should be taken that the cause is good, and that God's blessing may be safely implored in it.

France has lately fasted and prayed that they might be able to subjugate Spain, restore and establish the horrible inquisition, and utterly destroy all the liberties of the people! Is this such a fast as God hath chosen? - a.d. 1823.