Rescue me, O my God, from the hand of the wicked,
from the grasp of the unjust and cruel man.
For you, O Lord, are my hope,
my trust, O LORD, from my youth. Psalms 71:4-5
The psalmist continues his appeal to God. But now he gives reasons why God should respond and rescue him. ('For…') God is his hope and his trust. What does that mean and why does the psalmist think that it will move God to act?
This is what the psalmist is expressing in these words: 'God, as I face this difficult situation I have hope for rescue. And that hope is not about me or something that I will do to get me out of this fix. My hope is that you will act, that you will rescue me. I am entrusting myself and my life to you.' That seems clear.
But why should this response of the author move God to respond? Well, in effect, the psalmist is telling God: 'I am doing what you told me to do. Now do what you said you would do. Do what you promised me if I proved faithful, if I believed your promises.' Remember that the psalmist is in a covenant relationship with this God. 'I will be your God and you will be My people.' The psalmist is being faithful to his calling to live as one of the people of God. He is placing his hope in his God. He is trusting Him. His prayer is an expression of his faith. This is exactly how our friend is supposed to respond to his situation. This is how God wants him to respond. So, in a way, he is telling God, 'I am fulfilling what you have called me to do: to act like one of your people is supposed to act. So, I ask that You would do what you are supposed to do: be my God.' In this situation, that means rescue. The psalmist is leaning on that covenant relationship, expecting God to come through as He had promised. His prayer is showing his faith in God's covenant, both by fulfilling his part and expecting God to do the same. He expects his faithful obedience to God's call to move God to act on his behalf.
Seeing what the psalmist is praying in this light we are encouraged to be very bold in our prayers. Like the psalmist, we can call God to keep His word to us and to be whatever it means to be God to us in the situation that we are facing.