Passage
For thou hast possessed my reins; thou didst cover me in my mother's womb.
For thou hast possessed my reins; thou didst cover me in my mother's womb.
Psalms 139:11 And if I say, Surely darkness shall cover me, and the light about me be night;
Psalms 139:12 Even darkness hideth not from thee, and the night shineth as the day: the darkness is as the light.
Psalms 139:13 For thou hast possessed my reins; thou didst cover me in my mother's womb.
Psalms 139:14 I will praise thee, for I am fearfully, wonderfully made. Marvellous are thy works; and [that] my soul knoweth right well.
Psalms 139:15 My bones were not hidden from thee when I was made in secret, curiously wrought in the lower parts of the earth.
The verse centers on "thou", "hast", "possessed", "reins", "didst", "cover", and "mother's". It is saying that the verse draws attention to "thou" and "hast", so its meaning should be read from those terms before moving to application.
The nearby context moves from verse 12's "Even darkness hideth not from thee and..." into verse 14's "I will praise thee for I am...", so "thou" and "hast" belong inside that flow. In Psalms context, the local focus is worship, trust, the LORD's kingship, and covenant mercy.
A plain takeaway is to answer the verse's own emphasis on "thou" and "hast" with trust shaped by these words, not by a vague optimism outside the passage.