Unite my heart to fear your name. --Psalm 86:11
The verb used here for 'fear' very often in the psalms means something close to 'trust.' Yield to, bank on, submit to, count on, revere, bow before.
And here David asks the Lord to enable him to fear him, but the way he asks God to get him there is interesting. David asks the Lord to 'unite' (the verb form of the Hebrew word 'one') his heart.
The great insight of this verse is that a fallen human heart is a divided human heart. David feared/trusted God. But that was one impulse in his soul among many. He wanted a united heart. A whole heart. A heart not frenetically pulled in all kinds of directions fueled by an army of anxieties. A heart that wakes in the middle of the night and soothes its festering worries with this thought: God is my portion--period. A heart in which many valid goals and desires of various kinds are cultivated, but all of which funnel down into the supreme goal to fear God, to quietly bow before him in reverence and worship, to plant all one's hopes squarely on him.