Albert Barnes Commentary Psalms 138:6

"For though Jehovah is high, yet hath he respect unto the lowly; But the haughty he knoweth from afar." — Psalms 138:6 (ASV)

Though the Lord be high - This might be rendered, “For lofty is Yahweh—and the humble He sees—and the proud He knows from afar.” The idea is that God—so high and exalted—sees and knows all people of every rank.

The psalmist’s mind had been impressed with a sense of God’s greatness and majesty. However, (as if it might be said that one so great could not regard humanity, so humble and insignificant) he adds that God’s exaltation does not prevent Him from noticing the affairs of people. Therefore, the lowly in life need not fear that they will be overlooked, nor should the proud hope that they will escape the notice of His eye.

yet hath he respect unto the lowly - Those in humble life; the obscure; the unknown. It does not mean here that He has any special favor toward them, but merely that He sees them. Their low and obscure condition does not prevent Him from observing them, and they need have no fear that He will overlook them or that they will be forgotten. Compare the notes on James 4:6 and 1 Peter 5:5.

but the proud - Those of lofty rank, and of lofty feelings; the haughty.

he knoweth afar off - From afar. Though He is exalted—though He is in heaven—yet He is not so far removed that He does not see them and know them altogether. Distance from Him is no protection for them; nor can the wicked hope to escape notice from the fact that God reigns over distant worlds.