'Myself' in the Bible

May the Lord be good and true to you: and I myself will see that your kind act is rewarded, because you have done this thing.

And I will do even worse than this, and make myself even lower in your eyes: but the servant-girls of whom you were talking will give me honour.

And he said, While the child was still living I went without food and gave myself up to weeping: for I said, Who is able to say that the Lord will not have mercy on me and give the child life?

And David sent the people out, a third of them under the orders of Joab, and a third under the orders of Abishai, son of Zeruiah, Joab's brother, and a third under Ittai the Gittite. And the king said to the people, And I myself will certainly go out with you.

And I was upright before him, and I kept myself from sin.