Stretching My Hand Against the Lord's Appointed

David also said, "As the LORD lives, surely the LORD will strike him (Saul), or his day will come that he dies, or he will go down into battle and perish. The LORD forbid that I should stretch out my hand against the LORD'S anointed; but now please take the spear that is at his head and the jug of water, and let us go."(1 Samuel 26:10,11)

Here is the second time David has spared Saul's life. Considering that all of David's problems were caused by King Saul, it hardly seems wise for David not to kill him and avoid all the danger, uncertainty and inconvenience. But David did not want to stop his suffering before God decided to do so. He did not think it his place to kill the Lord's chosen king and left it to Him.
This passage reminds me of this place in Matthew's Gospel:

And behold, one of those who were with Jesus reached and drew out his sword, and struck the slave of the high priest and cut off his ear. Then Jesus said to him, "Put your sword back into its place; for all those who take up the sword shall perish by the sword. Or do you think that I cannot appeal to My Father, and He will at once put at My disposal more than twelve legions of angels? How then will the Scriptures be fulfilled, which say that it must happen this way?"(Matthew 26:51-54)

Peter tried stopping Jesus' suffering before it was God's time to end it. Jesus was determined to suffer to the extent decided by the Father. So, be way of application, I think that I am sometimes tempted by an opportunity to end whatever difficult time I may be going through. I should be patient to wait until God Himself ends it. Like He did with David and later with Jesus.