The picture is from a law court. Here are two very different witnesses.
The faithful witness is the believer in God. He has a constant sense of living in the presence of God and views his whole life as witness to the truth: a witness before men of the truth that God has revealed to him in secret. He may not actually be under oath, but he makes conscience of every word he speaks and knows that the Lord is watching the innermost movements of his soul which are not visible to anyone else. He examines his heart and detects all cunning and deceit within him, acting quickly to put it to death at the earliest stage, and not to let it bear fruit in the form of words or deeds. In this sense the Christian lives the whole of his life in the courtroom of the Lord, coming voluntarily and early to that place where he must be brought finally to give account at the last day. But there are Christians who have forgotten that they are walking under the gaze of God and that he sees them, so they justify everything they want to have; they justify their spiritual laziness and the way they live.