After Rebekah plots deception against her husband, she and Jacob now bring this deception to pass before Isaac, bringing confusion and untruthfulness before him, before he is to give the blessing to Esau. In so doing, they do not bring truth and God’s word to Isaac, and therefore they do not act in holiness.
Additional Scripture:
Proverbs
14:25-26, Matthew
12:34-35, Exodus 20:3-6