He opens their ears to instruction describes how God continues to deal with them. This verse repeats some of Elihu’s talk in 33.16. Opens their ears means “to cause to pay attention,” or as Good News Translation says, “He makes them listen.” The phrase translated to instruction means “to his warning”; that is, “He makes them pay attention to his warning.”

And commands that they return from iniquity: commands here renders the verb “says,” which when followed by the content of the indirect address usually means “to order or to command.” Return from iniquity is an idiom meaning “to return from evil to God” or “turn away from evil,” as in Good News Translation. The sense is “to stop doing evil, renounce evil, give up wickedness, repent.” Verse 10 may also be rendered “He makes them listen carefully and orders them to stop their evil ways” or “He sharpens their hearing and tells them to repent of their sins.”

Quoted with permission from Reyburn, Wiliam. A Handbook on Job. (UBS Helps for Translators). New York: UBS, 1992. For this and other handbooks for translators see here .