Jamieson, Fausset and Brown on Job 31:38

38. Personification. The complaints of the unjustly ousted proprietors are transferred to the lands themselves (Job 31:20; Ge 4:10; Ha 2:11). If I have unjustly acquired lands (Job 24:2; Is 5:8).

furrows--The specification of these makes it likely, he implies in this, "If I paid not the laborer for tillage"; as Job 31:39, "If I paid him not for gathering in the fruits." Thus of the four clauses in Job 31:38, 39, the first refers to the same subject as the fourth, the second is connected with the third by introverted parallelism. Compare Jas 5:4, which plainly alludes to this passage: compare "Lord of Sabaoth" with Job 31:26 here.