If your soul, i.e. your person, as Genesis 12:5. I could heap up words against you, i.e. I could multiply accusations and reproaches against you, as you do against me. Shake mine head at you; in way of derision, as this phrase is most commonly used; as 2 Kings 19:21 Psalms 22:7 Isaiah 37:22 Matthew 27:39.
Related Commentaries of Job 16:4
Job 16:4
4 I also could speak as ye do: if your soul were in my soul's stead, I could heap up words against you, and shake mine head at you.