Psalm 17:3 “Though you probe my heart and examine me at night, though you test me, you will find nothing;”
[Here is a statement I find hard to understand. I cannot say this–only a slight probe in me will find a multitude of wrong in my actions and thoughts, to say nothing of my heart.
Perhaps David was speaking more of the fact that he has not responded incorrectly in his present situation; maybe he has forgiven and prayed for the good of his enemies. Perhaps he has already confessed his sin in the situation and now stands cleansed as far as he knows.]
“I have resolved that my mouth will not sin.”
[He’s not going to give a response of the flesh, but speak what he knows is pleasing to you. That hints at checking his motives, thinking through his possible responses and choosing to obey what he knows is right. May I live like that.]
Psalm 17:4 “As for the deeds of men—by the word of your lips I have kept myself from the ways of the violent.”
[Perhaps here David, who was a man of war, is talking specifically of the instance before him where he did not respond to these people in violence (which he could have done), acting instead according your commands in grace and quietness. May I do the same!]
Psalm 17:5 “My steps have held to your paths; my feet have not slipped.”
[As David sought to obey, running in the paths prepared by you, Lord, he did not stumble or fall. It was only when he strayed from the path that he slipped, fell and took many others down with him.
Lord keep me on your path, surround me with your hedge of thorns, pricking me immediately when I zig or zag off your way. May I not slip and bring you dishonor.]