John Gill

Behold, ye fast for strife and debate,.... Brawling with their servants for not doing work enough; or quarrelling with their debtors for not paying their debts; or the main of their religion lay in contentions and strifes about words, vain hot disputations about rites and ceremonies in worship, as is well known to have been the case of the reformed churches: and to smite with the fist of wickedness; their servants or their debtors; or rather it may design the persecution of such whose consciences would not suffer them to receive the doctrines professed; or submit to ordinances as administered; or comply with rites and ceremonies enjoined by the said churches; for which they have smitten their brethren that dissented from them with the fist, or have persecuted them in a violent manner by imprisonment, confiscation of goods, &c.; all which is no other than a fist of wickedness, and highly displeasing to God, and renders all their services unacceptable in his sight; see Mat 24:49, ye shall not fast as ye do this day; or, "as this day"; after this manner; this is not right: to make your voice to be heard on high; referring either to their noisy threatening of their servants for not doing their work; or their clamorous demands upon their debtors; or to their loud prayers, joined with their fasting, which they expected to be heard in the highest heaven, but would be mistaken; for such services, attended with the above evils, are not wellpleasing to God.