O LORD, you have probed me and you know me;
you know when I sit and when I stand;
you understand my thoughts from afar.
My journeys and my rest you scrutinize,
with all my ways you are familiar.
Where can I go from your spirit?
From your presence where can I flee?
If I go up to the heavens, you are there;
if I sink to the nether world, you are present there.
If I take the wings of the dawn,
if I settle at the farthest limits of the sea,
Even there your hand shall guide me,
and your right hand hold me fast.
Truly you have formed my inmost being;
you knit me in my mother’s womb.
I give you thanks that I am fearfully, wonderfully made;
wonderful are your works.
(Psalm 139:1-3, 7-10, 13-14)
This is the first psalm of entreaty in this group of psalms of David (Ps 138–145), and by being positioned here it reads as an extension to the prayer of the exile (cf. Ps 137). Adopting the sort of feelings David might have had when he was fleeing from one place to another, it acknowledges that, wherever we are, we can be seen by God and he will call us to account for our actions. The psalm has a number of links with the previous one: God’s plans with regard to the psalmist (cf. Ps 138:8) are now considered in more depth, though they are cloaked in mystery (Ps 139:7); and the psalmist’s enemies (cf. Ps 138:7) are now depicted as the enemies of God himself (Ps 139:22). So, the prayer of a man who feels the Lord’s hand upon him becomes deeper here: he appeals to God, acknowledging him to be all-knowing, almighty, his maker, a just judge. It all serves to make this one of the most beautiful psalms in the Bible.
The psalm begins by registering that God knows everything the psalmist does, and takes special care of him (vv. 1–6); even if he wanted to, the psalmist could not escape his gaze (vv. 7–12), for God is the one who made him and he has steered his life in accordance with his mysterious purposes (vv. 13–18). Therefore, the psalmist has recourse to the Lord, asking him to do away with the ungodly, but asserting that he himself is faithful to the Lord and submits to his judgment (vv. 19–24). At the end of the psalm, what v. 1 said was already done is made the subject of an entreaty.
When Christians pray this psalm, they can become more aware of their dependence on God, more trustful of him, closer to him through Jesus Christ, who “knows what is in man” (cf. Jn 2:25), and can experience the inner presence of the Holy Spirit, who “searches everything” (cf. 1 Cor 2:10). The psalm is a call to practice the “presence of God” more fervently.
– May the virtues of faith, hope, and love go with you today – DV.
 James Gavigan, Brian McCarthy, and Thomas McGovern, eds., Psalms and the Song of Solomon, The Navarre Bible (Dublin; New York: Four Courts Press; Scepter Publishers, 2003), 447–448.