Who hath put wisdom in the {x} inward parts? or who hath given understanding to the heart?

(x) In the secret parts of man.

Jamieson-Fausset-Brown Bible Commentary

36. inward parts . heart-But "dark clouds" ("shining phenomena") [Umbreit]; "meteor" [Maurer], referring to the consultation of these as signs of weather by the husbandman (Ec 11:4). But Hebrew supports English Version. The connection is, "Who hath given thee the intelligence to comprehend in any degree the phenomena just specified?"

heart-not the usual Hebrew word, but one from a root "to view"; perception.

Matthew Henry's Concise Commentary

38:25-41 Hitherto God had put questions to Job to show him his ignorance; now God shows his weakness. As it is but little that he knows, he ought not to arraign the Divine counsels; it is but little he can do, therefore he ought not to oppose the ways of Providence. See the all-sufficiency of the Divine Providence; it has wherewithal to satisfy the desire of every living thing. And he that takes care of the young ravens, certainly will not be wanting to his people. This being but one instance of the Divine compassion out of many, gives us occasion to think how much good our God does, every day, beyond what we are aware of. Every view we take of his infinite perfections, should remind us of his right to our love, the evil of sinning against him, and our need of his mercy and salvation.