Thine eyes did see my substance
It is one thing to understand that God knows all our thoughts and sees all our actions (v1-6) but it is quite another thing to actually invite it.
To the chief Musician, A Psalm of David. O LORD, thou hast searched me, and known me. Thou knowest my downsitting and mine uprising, thou understandest my thought afar off. Thou compassest my path and my lying down, and art acquainted with all my ways. For there is not a word in my tongue, but, lo, O LORD, thou knowest it altogether. Thou hast beset me behind and before, and laid thine hand upon me. Such knowledge is too wonderful for me; it is high, I cannot attain unto it. (Psalm 139:1-6 KJV)
David goes on to ask God to search his heart. In our prayers, do we invite this kind of scrutiny?
Search me, O God, and know my heart: try me, and know my thoughts: And see if there be any wicked way in me, and lead me in the way everlasting. (Psalm 139:23-24 KJV)
Part of the reason is that David realises he can’t get away from God anyway:
Whither shall I go from thy spirit? or whither shall I flee from thy presence? If I ascend up into heaven, thou art there: if I make my bed in hell, behold, thou art there. If I take the wings of the morning, and dwell in the uttermost parts of the sea; Even there shall thy hand lead me, and thy right hand shall hold me. If I say, Surely the darkness shall cover me; even the night shall be light about me. Yea, the darkness hideth not from thee; but the night shineth as the day: the darkness and the light are both alike to thee. (Psalm 139:7-12 KJV)
And he realises that when he was helpless and, as yet, unformed in the womb, it was a good thing that God could see him!
For thou hast possessed my reins: thou hast covered me in my mother’s womb. I will praise thee; for I am fearfully and wonderfully made: marvellous are thy works; and that my soul knoweth right well. My substance was not hid from thee, when I was made in secret, and curiously wrought in the lowest parts of the earth. Thine eyes did see my substance, yet being unperfect; and in thy book all my members were written, which in continuance were fashioned, when as yet there was none of them. (Psalm 139:13-16 KJV)
so he concludes that the fact that God knows all, is rather a good thing for him:
How precious also are thy thoughts unto me, O God! how great is the sum of them! (Psalm 139:17 KJV)
Just as in the womb it was only God who could see us and look after us, so in death it is only God who can remember what we were and bring our substance back from decay. Jonah sought to run away from God, finding himself at last in a more perfect and complete hiding place than anyone could deem possible — the belly of a fish, deep in the sea. It was a good thing for Jonah that God could still see him and hear his prayer! Should we not likewise rejoice in God’s knowledge of us in our waking lives? It may feel uncomfortable that He knows and sees everything, but ultimately it is that trait that saves us.