Adam Clarke on Exodus 22:6

If fire break out - Mr. Harmer observes that it is a common custom in the east to set the dry herbage on fire before the autumnal rains, which fires, for want of care, often do great damage: and in countries where great drought prevails, and the herbage is generally parched, great caution was peculiarly necessary; and a law to guard against such evils, and to punish inattention and neglect, was highly expedient. See Harmer's Observat., vol. iii., p. 310, etc.