This Bible contradiction is from the Skeptic's Annotated Bible.
Psalm 18:30 View context
[As for] God, his way [is] perfect: the word of the LORD is tried: he [is] a buckler to all those that trust in him.
Psalm 19:7 View context
The law of the LORD [is] perfect, converting the soul: the testimony of the LORD [is] sure, making wise the simple.
Hebrews 8:6-7 View context
But now hath he obtained a more excellent ministry, by how much also he is the mediator of a better covenant, which was established upon better promises.
For if that first [covenant] had been faultless, then should no place have been sought for the second.