Psalm 13:1
13:1 To the chief Musician, A Psalm of David. How long wilt
     thou forget me, O LORD? {a} for ever? how long wilt thou
     hide thy face from me?

     (a) He declares that his afflictions lasted a long time,
         and that his faith did not waver.

Psalm 13:2
13:2 How long shall I take {b} counsel in my soul, [having]
     sorrow in my heart daily? how long shall mine enemy be
     exalted over me?

     (b) Changing my purposes as the sick man does his place.

Psalm 13:4
13:4 Lest mine enemy say, I have {c} prevailed against him;
     [and] those that trouble me rejoice when I am moved.

     (c) Which might turn to God's dishonour: if he did not
         defend his.

Psalm 13:5
13:5 But I have trusted in thy {d} mercy; my heart shall rejoice
     in thy salvation.

     (d) The mercy of God is the cause of our salvation.

Psalm 13:6
13:6 I will sing unto the LORD, because he hath {e} dealt
     bountifully with me.

     (e) Both by the benefits past and by others to come.