English Basic Explanation - Chapter 139
In this Psalm David speaks of God's omniscience, His unlimited, comprehensive knowledge of all affairs on earth and even the unspoken thoughts of human beings. In perhaps the most stirring segment of this chapter (verses 7-12), David hypothetically considers various regions where he could perhaps attempt to escape from God's watchful eye: the heavens, the underground, across the sea and in darkness. But, as David acknowledges, God's presence and providence extends unlimitedly to the heavens above and to the depths of the earth below, and spans the entire width and breadth of the universe. And, of course, darkness does not interfere with the Almighty's visual capabilities.
David attributes God's unlimited knowledge of his actions and thoughts to the simple fact that it was God who brought him into existence in the first place. In verses 13-16 David speaks of the miracle of an infant's creation and development inside the womb. It is God, of course, who fashions the embryo, and thus He naturally has a thorough knowledge and understanding of the workings of the human being, and traces his every step and even his every thought.
In the concluding section of this chapter (verses 17-24), David avows his loyalty to God, his affection and admiration for the righteous, and aversion and contempt for the wicked. He essentially says to the Almighty, "You know my thoughts and feelings, so You are well aware of where my loyalties lie, and what my truest desires and ambitions are." Realizing that nothing can possibly be hidden from God, David has successfully ensured that even his deepest feelings and emotions are in accordance with the divine will, and proudly declares the complete subjugation of his body, mind and heart to the Almighty.