Charles Ellicott Commentary Psalms 139:18

"If I should count them, they are more in number than the sand: When I awake, I am still with thee." — Psalms 139:18 (ASV)

If I should ...—The original is more expressive:

“Let me count them—more than the sand they are many:
I have awaked—and still with thee.”

With the countless mysteries of creation and providence the poet is so occupied, that they are his first waking thought; or, perhaps, as the Hebrew suggests, his dreams are continued into his early thoughts.

“Is not the vision He? though He be not that which He seems?
Dreams are true while they last; and do we not live in dreams?”

TENNYSON: Higher Pantheism.