Hear the voice of God. This covenant was not kept by the Israelis. The word believer is used in the place of obedience in The New Testament. Obedience that was not observed by people because of their sinful nature was observed by Jesus Christ. Obedience and believing are one and the same.
Obedience brings holiness.
Disobedience arises out of disbelief. If a minister is ordered by his superior to do some work, the subordinate minister should immediately carry out his orders. That is holiness. Postponing to carry out the orders amounts to disobedience. Postponement itself is disobedience.