Who was David HaMelech?

King David was born to Yishai, a man who never sinned and died only because the sin of Adam, which is the source of death in the world. David grew up in a surround that questioned the legitimacy of his lineage as his grandmother was Ruth the Moabite. Until shmuel hanavi pronounced David “the king that hashem selected”, he was considered by his family to be a mamzer (bastard) and that Yishai was not his real father. This situation persisted until Samuel, the prophet, came and anointed David as King of Israel and said that David is of legitimate lineage and that his father is Yishai. David reigned seven years in Hebron and thirty three years in Jerusalem. He laid down the foundations for the Holy Temple in Jerusalem, composed the Biblical book of Tehilim (Psalms of David) and conquered Idumea, Moab and Syria besides all of the Land of Israel. G-d chose him to have an everlasting monarchy that as long as there will be a King in Israel, he will be from the seed of David. Our Righteous Messiah must be of the seed of David.