'Myself' in the Bible

And if ye do not hear these words, By myself I have sworn -- an affirmation of Jehovah, That this house is for a desolation.

Who is saying, 'I build for myself a large house, And airy upper chambers,' And he hath cut out for himself its windows, Ceiled with cedar, and painted with vermilion.

For, by Myself, I have sworn, An affirmation of Jehovah, That for a desolation, for a reproach, For a waste, and for a reviling -- is Bozrah, And all her cities are for wastes age-during.