13 Confidence in the Lord’s ability to discern and perceive the nature and needs of his people comes from a belief in God’s purpose. He is the Creator, and his creative concerns include individuals.
In a sense this section continues the emphasis on divine involvement by an emphatic use of “you” (ʾattâ, vv. 2, 13: “you know … you created”) and by the use of the pronominal prefixes and suffixes to the verbs and nouns in Hebrew (translated by “you” and “your”). The Lord has formed the individual as a spiritual (“you created [qānâ, GK 7865; Ge 14:22; Pr 8:22] my inmost being [‘kidneys’],” v. 13) and a physical being (“you knit me together”; cf. Job 8–11; Jer 1:5). All beings owe their existence to the Creator-God. How much more the individual who walks with God, who knows that the Lord has formed him or her for a purpose.
14 Creation is existential! The intensely personal language to which the psalmist returns (“I” and “my”) complements that of the second section. God is concerned with the individuals he has formed for his purpose. Therefore praise is the proper response to God’s grace of discernment, perception, and purpose. The child of God sees God’s presence everywhere (vv. 7–12) and experiences the joy of God’s watchful eye over him. All God’s “works” are “wonderful,” but the believer, more than any other part of God’s creation, senses that he is “fearfully and wonderfully made.” Though God’s grace toward him is like “knowledge … too wonderful for” him to comprehend (v. 6), he lives with a personal awareness of God’s gracious purpose (“I know that full well”). The psalmist reveals a unique awareness of God’s grace toward him and responds with a hymn of thanksgiving (“I praise you”).
For his omnipotence (vv. 13–14)
God’s power is evidenced by his creation of each individual. God created our ‘reins’ (our innermost being, that is, those things that control us—minds, hearts, wills). He ‘covered’ us while we were in the womb. The word ‘covered’ may also be translated ‘knit’ or ‘wove’. By using this term the psalmist pictures himself as a fine piece of art and God as a skilled craftsman.
The psalmist’s conclusion is that he is ‘fearfully and wonderfully made’. Henry writes: ‘… we may justly be astonished at the admirable contrivance of these living temples, the composition of every part, and the harmony of all together.’
Some of the newer translations render this phrase as a description of God—‘You are fearfully wonderful’, that is, a God who is so marvellous and wonderful that the only thing one can do is stand in awe of him.
It isn’t all that important which of the two translations we follow. A fearfully wonderful God can only do fearfully wonderful works.
David would have us know he is not just getting carried away with his own writing. He is not indulging in poetic licence. He says it is the deep conviction of his soul that all God’s works are marvellous (v. 14).
13. “For thou hast possessed my reins.” Thou art the owner of my inmost parts and passions: not the indweller and observer only, but the acknowledged lord and possessor of my most secret self. The word “reins” signifies the kidneys, which by the Hebrews were supposed to be the seal of the desires and longings; but perhaps it indicates here the most hidden and vital portion of the man; this God doth not only inspect, and visit, but it is his own; he is as much at home there as a landlord on his own estate, or a proprietor in his own house. “Thou hast covered me in my mother’s womb.” There I lay hidden—covered by thee. Before I could know thee, or aught else, thou hadst a care for me, and didst hide me away as a treasure till thou shouldst see fit to bring me to the light. Thus the Psalmist describes the intimacy which God had with him. In his most secret part—his reins, and in his most secret condition—yet unborn, he was under the control and guardianship of God.
14. “I will praise thee:” a good resolve, and one which he was even now carrying out. Those who are praising God are the very men who will praise him. Those who wish to praise have subjects for adoration ready to hand. We too seldom remember our creation, and all the skill and kindness bestowed upon our frame: but the sweet singer of Israel was better instructed, and therefore he prepares for the chief musician a song concerning our nativity and all the fashioning which precedes it. We cannot begin too soon to bless our Maker, who began so soon to bless us: even in the act of creation he created reasons for our praising his name. “For I am fearfully and wonderfully made.” Who can gaze even upon a model of our anatomy without wonder and awe? Who could dissect a portion of the human frame without marvelling at its delicacy, and trembling at its frailty? The Psalmist had scarcely peered within the veil which hides the nerves, sinews, and blood-vessels from common inspection; the science of anatomy was quite unknown to him; and yet he had seen enough to arouse his admiration of the work and his reverence for the Worker. “Marvellous are thy works.” These parts of my frame are all thy works; and though they be home works, close under my own eye, yet are they wonderful to the last degree. They are works within my own self, yet are they beyond my understanding, and appear to me as so many miracles of skill and power. We need not go to the ends of the earth for marvels, nor even across our own threshold; they abound in our own bodies.
“And that my soul knoweth right well.” He was no agnostic—he knew; he was no doubter—his soul knew; he was no dupe—his soul knew right well. Those know indeed and of a truth who first know the Lord, and then know all things in him. He was made to know the marvellous nature of God’s work with assurance and accuracy, for he had found by experience that the Lord is a master-worker, performing inimitable wonders when accomplishing his kind designs. If we are marvellously wrought upon even before we are born, what shall we say of the Lord’s dealings with us after we quit his secret workshop, and he directs our pathway through the pilgrimage of life? What shall we not say of that new birth which is even more mysterious than the first, and exhibits even more the love and wisdom of the Lord.
139:13–14. The theme of verses 13–18 is announced here: the Lord (You is emphatic in Heb.; cf. v. 2) created him in his mother’s womb. The language is figurative in that creating and knitting describe God’s sovereign superintendence over the natural process of reproduction (on knitting; cf. Job 10:11).
This fact prompted the psalmist to break forth in praise over the thought of how marvelously he had been made. Even David’s rudimentary knowledge of the marvels of the human body led him to be in awe and wonder. The words wonderfully and wonderful are mindful of God’s marvelous knowledge (Ps. 139:6).
139:13, 14 So much then for the omnipresence of God. David now turns to consider His power and skill. And the particular phase of divine omnipotence he chooses is the marvelous development of a baby in his mother’s womb. In a speck of watery material smaller than the dot over this i, all the future characteristics of the child are programmed—the color of his skin, eyes and hair, the shape of his facial features, the natural abilities he will have. All that the child will be physically and mentally is contained in germ form in that fertilized egg. From it will develop:
… 60 trillion cells, 100 thousand miles of nerve fiber, 60 thousand miles of vessels carrying blood around the body, 250 bones, to say nothing of joints, ligaments and muscles.
David describes the formation of the fetus with exquisite delicacy and beauty. “You formed my inward parts; You covered me in my mother’s womb.” Yes, God formed our inward parts; each one a marvel of divine engineering. Think of the brain, for instance, with its capacity for recording facts, sounds, odors, sights, touch, pain; with its ability to recall; with its power to make computations; with its seemingly endless flair for making decisions and solving problems.
And God knit us together in our mother’s womb. This aptly describes the marvelous weaving of the muscles, sinews, ligaments, nerves, blood vessels and bones of the human frame.
David bursts forth in praise to the Lord. As he thinks of man, the crown of God’s creation, he can only confess that he is fearfully and wonderfully made. The more we think of the marvels of the human body, its orderliness, its complexity, its beauty, its instincts and inherited factors—the more we wonder how anyone trained in natural science can fail to be a believer in an infinite Creator.
 MacDonald, W. (1995). Believer’s Bible Commentary: Old and New Testaments. (A. Farstad, Ed.) (p. 770). Nashville: Thomas Nelson.