Psalm 17  David writes prayer after prayer after prayer.   He pursues this deeper conversation with the Lord God.  He continually cries out to God and restates his commitment to obey and follow the Word of God.  This is why he is called a "man after God's own heart".   This prayer, like many that he has written, calls out for God's protection against the enemy.
 David states his honest and sincere need, but he qualifies his requests based on his commitment to the Lord.
"Hear a just cause, O Lord, give heed to my cry;"  David is careful to ask for what is just.( God will not answer unjust prayers will He?)
"Give ear to my prayer, which is not from deceitful lips."  James 42b-3 says " You do not have because you do not ask.  You ask and do not receive because you ask with wrong motives, so that you may spend it on your pleasures." David was careful to pray with sincere and truthful motives.
"Let my judgement come forth from Thy presence."  David submitted to the Lord's decisions.
"Let Thine eyes look with equity."   David trusted in the Lord's fairness.
You have tried my heart.
You have tested me.
I have purposed to only speak truth.
I have kept away from the path of violence.
I am walking in Your ways.  David examined himself and was doing everything he knew to do in obedience to God.
I call upon You for You will answer!  David was assured that God would hear and answer his prayers.

"Wondrously show Thy lovingkindness, O Savior of those who take refuge at Thy right hand.... Keep me as the apple of the eye; Hide me in the shadow of Thy wings."

Because the Lord is our refuge... and because we call upon Him with sincere and honest hearts, we can be assured that He hears us.   He does not answer because we have a just cause or because we have passed a test... He answers because of His wondrous love and kindness. Because He has chosen to make us the apple of His eye... because He delights in us.. we commit ourselves to walk in His ways and bring every need to Him with faith in His power to save.

Father in heaven,  bless Your Name forever and ever!  May men and women and children all over this earth give praise and honor to Your Holy Name.  Thank You for hearing our prayers and answering our requests.  Thank You for being so loving and kind. For choosing to delight in us and to save us from the enemy. We take refuge in You, O Lord, for You alone can help us.  We praise You with all our hearts.  Amen.