Who knoweth not in all these that the hand of the LORD hath wrought this?

Wesley's Notes

12:9 Lord - This is the only time that we meet with the name Jehovah in all the discourses between Job and his friends. For God in that age was more known by the name of Shaddai, the Almighty.

Jamieson-Fausset-Brown Bible Commentary

9. In all these cases, says Job, the agency must be referred to Jehovah, though they may seem to man to imply imperfection (Job 12:6; 9:24). This is the only undisputed passage of the poetical part in which the name "Jehovah" occurs; in the historical parts it occurs frequently.

Matthew Henry's Concise Commentary

12:6-11 Job appeals to facts. The most audacious robbers, oppressors, and impious wretches, often prosper. Yet this is not by fortune or chance; the Lord orders these things. Worldly prosperity is of small value in his sight: he has better things for his children. Job resolves all into the absolute proprietorship which God has in all the creatures. He demands from his friends liberty to judge of what they had said; he appeals to any fair judgment.