Keep a clear conscience
"But in your hearts set apart Christ as Lord. Always be prepared to give an answer to everyone who asks you to give the reason for the hope that you have. But do this with gentleness and respect, keeping a clear conscience, so that those who speak maliciously against your good behavior in Christ may be ashamed of their slander" (1 Peter 3:15-16).
Keep a clear conscience before God and men
"So I strive always to keep my conscience clear before God and man" (Acts 24:16).
You can have a clear conscience and rest in the heart
"My son, preserve sound judgment and discernment, do not let them out of your sight; they will be life for you, an ornament to grace your neck. Then you will go on your way in safety, and your foot will not stumble; when you lie down, you will not be afraid; when you lie down, your sleep will be sweet. Have no fear of sudden disaster or of the ruin that overtakes the wicked, for the LORD will be your confidence and will keep your foot from being snared" (Proverbs 3:21-26).
Conscience accuses of sin
"David was conscience-stricken after he had counted the fighting men, and he said to the LORD, "I have sinned greatly in what I have done. Now, O LORD, I beg you, take away the guilt of your servant. I have done a very foolish thing" (2 Samuel 24:10).
A guilty conscience can be cleansed
"...let us draw near to God with a sincere heart in full assurance of faith, having our hearts sprinkled to cleanse us from a guilty conscience and having our bodies washed with pure water" (Hebrews 10:22).
Jesus can cleanse your conscience
"How much more, then, will the blood of Christ, who through the eternal Spirit offered himself unblemished to God, cleanse our consciences from acts that lead to death, so that we may serve the living God" (Hebrews 9:14).