David was a man after God’s own heart for many reasons, Psalm 139 illustrates two of them.
First, He willingly strained himself to meditate seriously upon God’s divine characteristics—i.e. His omniscience (vv. 1-6), omnipresence (vv. 7-12), and omnipotence (vv. 13-16). He was not superficial in his thinking about God. He ever sought to realize the enormous chasm between his mortal limitations and Jehovah’s limitless nature.
Then, he sought to respond appropriately to God’s utter worthiness and live accordingly. Verses 17-18 contain David’s response to his profound meditations of verses 1-16. Here, it is written, “How precious also are Your thoughts to me, O God! How great is the sum of them! If I should count them, they would be more in number than the sand; when I awake, I am still with You.”
“More in number than the sand.” What a vast number that must be! David sought to make the sum of his thoughts of God as close to infinity as was possible for an earthbound creature. He truly sought to set his mind on things above, not on things on the earth (cf. Colossians 3:2). How deserving he is of the moniker “a man after God’s own heart” (1 Samuel 13:14).
If (or maybe I should say, When) your thoughts of God are added up, how close would they be to being more than the number of grains of sand found upon this earth?
Set your mind on things above!