When I call you to go through the deep waters I will be with you! I will not let you sink nor let the waves overcome you! When you walk through the fire you will not get burned! I am the Lord thy God [paraphrase]
Above all else, guard your heart, for everything you do flows from it. What is in our hearts comes out through our words and actions. We must guard our hearts from evil so that we can abstain from doing evil.