In this morning worship song, David leads the people 1) to pray for their own needs, 2) to pray against their enemies, and 3) to praise the Lord for His gracious help. What a wonderful way to start the day! Each of the worshippers who has gathered NEEDS to start the day with this kind of dependence upon the Lord, with this kind of reaffirmation of his/her relationship to Him in every aspect of daily life.
First then, they're led to confess their absolute dependence upon the Lord. They led to tell Him that in all likelihood they're going to be crying out to Him many times that day, and they will need Him to hear them each and every time. So they sing, "To You I will cry, O Lord my Rock: do not be silent to me!" They're asking the Lord not to "tune them out" on any of those occasions. Of course, He wouldn't actually "tune them out," but God would have them to pray for this mercy so that they'll be aware when He grants it.
Besides, the alternative is awful indeed! They sing, "Lest, if You are silent to me, I become like those who go down to the pit!" In other words, the singer confesses that his courage and success in each situation absolutely depends upon the Lord hearing, answering, and acting on his behalf. The "pit" is sheol, the place of the dead, and those who descend to it have no further hope from the Lord.
So he wants to be heard and answered each and every time he cries out to the Lord, each and every time he "lifts up his hands toward Your holy sanctuary." The sanctuary is the place God chose to meet with believers, the place where the ark was, the place that reminded every worshipper of His Providence and mercy during the exodus from Egypt - and of the mercy which he still needs NOW!
Having sung this prayer for his needs that day, the worshipper then prays against his enemies. He doesn't want to be drawn away with them or to become one with them, because they "speak peace with their neighbors, but evil is in their hearts." Instead, he prays that they will receive just recompense for their evil actions - since they are not only their enemies but the enemies of God.
We might tend to think that this is an unusually vindictive prayer, that prayer for the welfare of one's enemies is the only right approach. However, we need to be aware of two things: 1) this isn't a personal prayer against individuals, but a general prayer against enemies of God and of God's people. The worshipper who prays this prayer might at the same time pray for the repentance of individuals among those same enemies. 2) It's a matter of being on God's side against His enemies, so it's not merely a desire for personal revenge. We need to remember what he says about them here - that "they do not regard the works of the Lord, nor the operation of His hands." Paraphrased, this prayer says, "Lord, STOP them! Don't let them hinder Your work!" And He'll answer that prayer. The worshipper may actually believe it when he sings, "He shall destroy them and not build them up."
Finally, the leader leads each worshipper to praise the Lord for actually hearing and answering him! They sing, "The Lord is my strength and my shield; my heart trusted in Him, and I am helped; therefore my heart greatly rejoices, and with my song I will praise Him!" The Lord will hear and help during the coming day!
The song ends with a climactic chorus of praise to the God Who ALWAYS hears, Who ALWAYS blesses His dear covenant people, Who blesses them through their anointed King. So they joyfully sing that God "is their strength, and He is the saving refuge of His anointed."
Our Lord Jesus Christ is now our anointed King, and, through Him God will hear YOU today! So you too can have the confidence of the worshipper here, who closes by singing, "Save Your people, and bless Your inheritance; shepherd them also, and bear them up forever!"
Do you begin the day this way? Do you realize that there will be many, many times each day in which you're going to need His grace and strength, times that should prompt you to cry unto Him? Do you pray that He'll hear you each time? Do you realize that it isn't really your day, but His day, so that you're prayers will not only result in your success, but also in His glory in all that you do?