'Says the Lord' in the Bible

Go and tell my servant David, Thus says the LORD, Shall you build me a house for me to dwell in?

Now therefore so shall you say unto my servant David, Thus says the LORD of hosts, I took you from the sheepfold, from following the sheep, to be ruler over my people, over Israel:

And Nathan said to David, You are the man. Thus says the LORD God of Israel, I anointed you king over Israel, and I delivered you out of the hand of Saul;

Thus says the LORD, Behold, I will raise up evil against you out of your own house, and I will take your wives before your eyes, and give them unto your neighbor, and he shall lie with your wives in the sight of this sun.

Go and say unto David, Thus says the LORD, I offer you three things; choose you one of them, that I may do it unto you.