This verse has two parallel rhetorical questions that follow the interrogative pronoun Who. The questions imply that no one could possibly give the LORD advice.

Who has directed the Spirit of the LORD asks whether anyone can tell the LORD what to. The obvious answer is “No one!” The Hebrew verb rendered directed is the same one translated “marked off” in the previous verse. It can mean “to measure,” “to determine,” or “to fix [in a position].” Most modern versions have the sense of “direct” here, but New International Version suggests “understand,” which possibly follows the Septuagint. Translators may follow either sense. For the Spirit of the LORD, see the comments on 11.2 and Isa 40.7, where the Hebrew phrase here is rendered “the breath of the LORD.” In this context a good rendering is “the mind of the LORD.” For the whole question Good News Translation provides a nonfigurative rendering with “Can anyone tell the LORD what to do?” New International Version has “Who has understood the mind of the LORD…?” New Jewish Publication Society’s Tanakh is similar with “Who has plumbed the mind of the LORD…?” Bible en français courant says “Who has taken the measure of the Spirit of the Lord?” This rendering expresses the meaning well, but it is better not to capitalize the word “Spirit” since it implies the Holy Spirit.

Or as his counselor has instructed him is literally “and a man of his counsel [or, his counselor] caused him to know.” This question implies that God does not need anyone to give him instructions on how to do his work. New Jerusalem Bible expresses it well with “what counsellor could have instructed him?”

For the translation of this verse consider the following examples:

• No one can direct the mind of the LORD,
no one can give him advice as his counselor.

• Who could comprehend the LORD’s mind?
Which counselor could teach him?

• Who can take the measurement of the mind of the LORD
or give him advice as his counselor?

Quoted with permission from Ogden, Graham S. and Sterk, Jan. A Handbook on Isaiah. (UBS Helps for Translators). New York: UBS, 2011. For this and other handbooks for translators see here .