Verse 6
My righteousness I hold fast - I stand firmly on this ground; I have endeavored to live an upright life, and my afflictions are not the consequence of my sins.
My heart shall not reproach me - I shall take care so to live that I shall have a conscience void of offense before God and man. "Beloved, if our heart condemn us not, then have we confidence toward God;" 1Jn 3:21. This seems to be Job's meaning.