I will also praise you with the harp
for your faithfulness, O my God;
I will sing praises to you with the lyre,
O Holy One of Israel.
My lips will shout for joy,
when I sing praises to you;
my soul also, which you have redeemed.
And my tongue will talk of your righteous help all the day long,
for they have been put to shame and disappointed
who sought to do me hurt. Psalm 71.22-24
Our Psalm closes, appropriately, with the psalmist praising his God. And he is specific about his praises. He praises God for His faithfulness. Our friend has found that his - and our - God keeps His promises. And that has evidenced itself as the psalmist has had to deal with those 'who sought to do me hurt'. Remember that he has prayed, 'Rescue me, O my God, from the hand of the wicked, from the grasp of the unjust and cruel man.' And God, having promised to do that, came through. He praises God because he has been redeemed, that is, rescued. And the psalmist pledges to let others know about what his God has done. 'And my tongue will talk of your righteous help all the day long.' It is that help that brought shame and disappointment on his enemies. There has been justice.
We all have experienced the goodness of God. He has kept His promises to us, rescued us, helped us. Sometimes the enemies that have confronted us have been other people. But it's more likely that our enemies have been our own sins. And, of course, in both cases Satan and his devils are involved. But in each case as we have cried out our God has responded. And for that we all can praise Him.