Yet these things thou didst hide in thy heart: these things refers to the things which Job is about to mention in verses 14-17 and is paralleled by this in the next line. Job is about to tell openly the things which God has been keeping secret. Hide in thy heart means to keep them secret, not to let anyone know about them. The whole line may be rendered “What I will tell now you have kept secret,” “You did not let me know what you were planning to do,” or “You did not let anyone know the things you would do to me.” I know that this was thy purpose: this line has a parallel in 27.11 “I will not conceal the purpose of the Almighty” (New English Bible). In Job’s view God’s kindness in his earlier happy life was part of God’s cruel plan to ruin him. So he says now “I know that you were planning to do these things to me.”

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 .