Isaiah 40:13 - Ellicott's Commentary On The Whole Bible

Who hath directed the Spirit of the Lord? — The term, which had been used in a lower sense in Isaiah 40:7, is here clothed as with a Divine personality, answering, as it were, to the wisdom of Proverbs 8:22-30, with which the whole passage has a striking resemblance. Eastern cosmogonies might represent Bel or Ormuzd, as calling inferior deities into counsel (Cheyne). The prophet finds no other counsellor than One who is essentially one with the Eternal.