'Saith' in the Bible

Go and tell David my servant, Thus saith the LORD, Thou shalt not build me an house to dwell in:

Now therefore thus shalt thou say unto my servant David, Thus saith the LORD of hosts, I took thee from the sheepcote, even from following the sheep, that thou shouldest be ruler over my people Israel:

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

So Gad came to David, and said unto him, Thus saith the LORD, Choose thee