John Gill Commentary Psalms 28:6

"Blessed be Jehovah, Because he hath heard the voice of my supplications." — Psalms 28:6 (ASV)

Blessed [be] the Lord Which must be understood, not as invoking nor as conferring a blessing on him, neither of which can be done by a creature; nor does he stand in need of any, he being Elshaddai, God all sufficient, God over all, blessed for ever; but as ascribing all blessedness to him, congratulating his greatness and happiness, and giving him praise and glory for mercies received; and particularly for the following:

because he has heard the voice of my supplications ; what he had prayed for, (Psalms 28:2); an answer was quickly returned, even while he was speaking, (Isaiah 65:24); though this may be an expression of faith, being fully persuaded and assured that he was heard, and would be answered, and may be said by a prophetic spirit; knowing that what he had humbly asked for would be granted; so Aben Ezra and Kimchi understand it in a way of prophecy.