Psalm 139:6

[Such] knowledge [is] too wonderful for me
Meaning either the knowledge of himself, such as God had of him, which was vastly superior to what he had of himself; and especially the knowledge of other persons and things, whether visible or invisible, in heaven, earth, or hell; things past, present, and to come; or else the manner in which God knew all this was amazing to him, and quite impenetrable by him; that he did know him, his thoughts, his words and actions, and so those of all others, was easy of belief; but how he should know all this was past his conception, and struck him with the profoundest admiration;

it is high;
sublime, out of his reach, beyond his comprehension;

I cannot [attain] unto it;
neither to such knowledge, nor to comprehend what it is in God; and how he should have it, and in what manner he exercises it. Kimchi, Jarchi, and Aben Ezra, connect the words with the following, as if the matter of his wonder and astonishment was the omnipresence of God, or where he should find a place to flee from him.