These people were guilty of saying “harsh things” against the Lord. For one thing, they felt that serving the Lord was useless; it was futile to be His servants. The priests may have been leaders in this complaining, but the common people were just as guilty. “We’re not getting anything out of it” was their grievance. “Things just keep getting worse”. We serve God because it’s the right thing to do, not because we’re rewarded for our service. We shall be rewarded, but that is not our main motive.