Does God want us to be motivated by his rewards?

For a very long time people have been singing of their great reward. And not only Americans.
The Hebrew book of worship, the Psalms, is prefaced by the following:

Blessed is the man
 who walks not
In the counsel of the wicked,
Nor stands in the way of sinners,
Nor sits in the seat of scoffers;
But his delight is in the law of the Lord,
And on his law he meditates day and night.
He is like a tree
 planted by streams of water
That yields its fruit in its season,
And its leaf does not wither.
In all that he does, he prospers.
-Ps 1:1-3

Here are 50 of my favorite lines of blessing in the hymns.