Jamieson, Fausset and Brown on Hebrews 4:13

13. creature--visible or invisible.

in his sight--in God's sight (He 4:12). "God's wisdom, simply manifold, and uniformly multiform, with incomprehensible comprehension, comprehends all things incomprehensible."

opened--literally, "thrown on the back so as to have the neck laid bare," as a victim with neck exposed for sacrifice. The Greek perfect tense implies that this is our continuous state in relation to God. "Show, O man, shame and fear towards thy God, for no veil, no twisting, bending, coloring, or disguise, can cover unbelief" (Greek, 'disobedience,' He 4:11). Let us, therefore, earnestly labor to enter the rest lest any fall through practical unbelief (He 4:11).