1 Kings 8:56 (ESV)

56 “Blessed be the LORD who has given rest to his people Israel, according to all that he promised. Not one word has failed of all his good promise, which he spoke by Moses his servant.

When we see in the Bible a blessing pronounced on the Lord, rather than a blessing pronounced by the Lord on someone else, a question may come to mind. How is it possible for a creature to bless God the Creator? In the first place, he does not stand in need of anything, for he is complete in himself. Second, he is the source of every blessing and therefore already possesses all blessedness. A look at the Hebrew root of the verb can also give the interpreter some difficulty. It carries with it the idea of kneeling as in worship. Yet, God kneels to no one. What are we to make of these things? The best answer we can give is to suggest that when Scripture calls a blessing on God, it is for the purpose of demonstrating a reason or reasons for God to be worshipped. In other words, we are given reasons to kneel before him in worship.

The reason to bless, that is, to worship, the Lord that Solomon pronounces is that he has given rest to his people as he accomplished by the multitude of promises that he gave to them, none of which was broken. We are to remember also that though some of these promises were conditional, God has performed them as if they were unconditional. Thus, Solomon was urging the people to acknowledge the grace of God.