Or, is it, in fact because he actually understands the law in a way we don't? That the singer of Psalm 119 has made the vital link between the law and the promise, and therefore the law and Christ. He can delight in the law because he understands it...really understands it. It has invaded every area of his heart.
This is Christopher Ash's thesis in his book 'Bible Delight' a section by section exposition and application of psalm 119. He explains that the reason the singer can delight in the law is because he knows the law is a gracious, covenant document. So the law looks like this to his heart:
1) Although he lives in a world of false gods, he is learning to love the LORD his God who redeemed him, and love no others.
2) Although he lives in a world of idols, he is learning to hate idolatry, the shaping and fashioning of gods to be the way man wants them to be.
3) In a world that holds the name of God cheap, he is learning to love God's name and to care for it's honour, not to cheapen the name by the way he speaks or behaves.
4) In a frenetic and anxious world, he is learning to love the sabbath principle. He has tasted the goodness and sufficiency of God and will therefore gladly rest, and allow others to rest with him.
5) In a disordered world, he will honour his parents. he understands that this commandment is the tip of the iceberg for him to honour all those in positions of authority over him.
6) In a world of hate and anger he is learning to shun any behavior that harms or desires to harm another human. He now wants to love his neighbour as himself.
7) In an unfaithful world, he is learning to value sexual faithfulness within the covenant of marriage and to flee from all other sexual intimacy.
8) In an unjust world, he is learning to hate stealing and unjust business dealing. He is learning to love justice and work hard so he will have something to share, because he knows the God who richly gives us all things to enjoy.
9) In a deceitful world, he hates false witness, lying for our gain and anothers harm. He is learning to love truth because he knows the God who's promises are always 'yes' in Christ.
10) In a self obsessed world he is learning to hate selfishness and greed because he is learning to trust the God who said 'i will never leave you nor forsake you'
Bible Delight, PP40-41, Christopher Ash