Job 39:9 - Ellicott's Commentary On The Whole Bible

The unicorn. — It is a mistake to identify this animal with the rhinoceros, as was formerly done; it is more probably the same with the buffalo, or wild ox. The most glaring form of the mistake is in Psalms 22:22 : “Thou hast heard me also from among the horns of the unicorns” The way in which the animal is here spoken of, as in analogous contrast to the domestic ox, suggests that it is not wholly dissimilar. It is familiar and homely toil that the wild ox is contemplated as being put to, in the place of tame cattle, whose work it is.