Adam Clarke on Job 21:29

Have ye not asked them that go by the way? - This appears to be Job's answer. Consult travelers who have gone through different countries; and they will tell you that they have seen both examples - the wicked in great prosperity in some instances, while suddenly destroyed in others. See at the end of the chapter, Job 21:34 (note).

Do ye not know their tokens - Mr. Good translates the whole verse thus: "Surely thou canst never have inquired of men of travel; or thou couldst not have been ignorant of their tokens. Hadst thou made proper inquiries, thou wouldst have heard of their awful end in a thousand instances. And also of their prosperity." See at the end of this chapter, Job 21:34 (note).