Psalms 26:3

For thy loving-kindness is before mine eyes - Thy favor or friendship is constantly before me, in the sense that it is the object of my desire. I wish to secure it; I long to know whether I have sufficient evidence that it is mine. This is a reason why he desires that God would search him. The favor or the friendship of God was an object of intense desire with him. He had evidence upon which he relied, and which seemed to him to be satisfactory, that God was his friend. But the object was so great, the matter was so important, the danger of self-deception was so imminent, that he did not dare to trust his own judgment, and he prayed that God would search him. The thought here is, that it was a steady purpose of his life to secure the favor of God. His eye was never turned from this. It was always before Him.

And I have walked in thy truth - I have embraced the truth; I have regulated my life by the truth. This is the first thing to which he refers. He was certain that this had been his aim. Compare the notes at 3 John 1:4. See also 2 Kings 20:3. One of the first characteristics of piety is a desire to know what is true, and to live in accordance with the truth. The psalmist was conscious that he had “arrived” at this, and that he had endeavored to make it a ruling principle in his conduct. Whether he had done this, or whether he had deceived himself in the matter, was what he now wished to submit to the all-searching eye of God.