'Says the Lord' in the Bible

Go and tell David my servant, Thus says the LORD, You shall not build me a house to dwell in:

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

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

So Gad came to David, and said unto him, Thus says the LORD, Choose you