Rashi on Exodus 22:5/רש"י על שמות כ״ב:ה׳

1כי תצא אש IF A FIRE GOETH FORTH — i. e. even if it goeth forth (extends) by itself (Bava Kamma 24b) from the field in which it has been lit into another persons field.

2ומצאה קוצים AND CATCH IN THORNS —chardons in old French

3ונאכל גדיש SO THAT THE STACKS OF CORN [OR THE STANDING CORN] BE CONSUMED, because it (the fire) licked up the thorns and gradually reached the stacks of corn or the standing corn, i. e. corn that is still attached to the ground.

4או השדה OR THE FIELD — because it (the fire) liked up his furrow (the newly broken soil), so that it became hard and he (the owner) has to plough it again (Bava Kamma 60a).

5שלם ישלם המבער HE THAT KINDLED [THE CONFLAGRATION] SHALL SURELY PAY — Although he has lit the fire on his own soil and it extended by itself through the thorns which it came across, he has to make restitution because he did not guard his fire (lit., burning coals) that it should not extend and cause damage.