He Rejoices Because He Knows That YHWH Has Heard Him And Will Be His Strength (Psalms 28:6-7).
His thoughts now become more positive. The negative was necessary, but now he begins to look upward. He has prayed through to a point of confidence and faith. And the more he prays the greater his faith. (‘This kind goes out only through prayer' - Mark 9:29, for it is prayer that produces growth in faith).
‘Blessed be YHWH, because he has heard
The voice of my supplications.'
He begins by blessing God for having heard his pleas. The fears of Psalms 28:1 b have departed, and he praises Him for listening to his supplications. It is a reminder to us that however dead our prayers might appear, if we genuinely approach Him in Jesus' Name (with His good in mind, not ours), we can be sure that they are being attended to.
‘YHWH is my strength and my shield,
My heart has trusted in him, and I am helped,
Therefore my heart greatly rejoices,
And with my song will I praise him.
And having blessed God, he now firmly establishes himself on what he knows about Him. It is He Who is the source of his strength, and is the great shield behind which he can take shelter. He knows that YHWH the Mighty Warrior, the God of battle, is acting on his behalf, both positively to give him the victory, and negatively to keep him from all harm, and that he is being helped. No wonder then that his heart rejoices and he is filled with praise. He knows that one with God is a majority. Note the order. He meditates on what God is on His behalf, then he is helped, and this causes him to rejoice in his heart, with the result that the praises break forth from his mouth.