Proverbs 15:26 (NKJV)
The thoughts of the wicked are an abomination to the Lord, But the words of the pure are pleasant.
When we think of sin, usually we think of sins of commission in which something wrong is done like lying, stealing or killing. We might even consider those sins where a good or right thing was left undone like failing to be kind or failing to be obedient. These would be sins of omission. Perhaps the most pernicious sin is that of the thought life where no one but you and God can see. God, I pray that my thoughts and my words would be pleasing to you.