Albert Barnes Commentary Psalms 119:2

"Blessed are they that keep his testimonies, That seek him with the whole heart." — Psalms 119:2 (ASV)

Blessed are they that keep his testimonies - His commandments or laws, considered as what he bears witness to concerning that which is just, wise, good. Every law of a parent is to his children a testimony on his part of what is wise and right and good; and so every law of God is his solemn testimony as to what is right and good for man. See Psalms 19:7, note; Psalms 25:10, note.

And that seek him with the whole heart - With a sincere desire to know his will and to do it; without hypocrisy or guile; with no selfish or sinister aims. As God knows the heart, all other modes of seeking him must be in vain. It is impossible for man to impose on him by appearances.