My reins also instruct me— By reins is meant the secret thoughts and inward reflections of the mind; in the same manner as the heart is often mentioned to express the hidden purposes and desires of the soul. See Psalms 7:10; Psalms 26:2.Jeremiah 12:2.Revelation 2:23.
Related Commentaries of Psalms 16:7
Psalms 16:7
7 I will bless the LORD, who hath given me counsel: my reins also instruct me in the night seasons.