Had sworn with an oath; not barely had sworn, which had been sufficient; but to show the excellency of the matter, and the necessity of our believing of it, as also the solemnity of the words, Psa_132:11.
Of the fruit of his loins; such as should descend from him, as the virgin Mary did.
According to the flesh; as to his human nature, which our Saviour did truly partake of, being in the form of a servant.
He would raise up Christ, by the power of the Holy Ghost in the womb of his virgin mother, as to his incarnation; and by the same power out of the grave, in his resurrection.
To sit on his throne; as Luk_1:32,33: not as a temporal king, for his kingdom is not of this world; but as David ruled over all the people of God, so does Christ, and shall do for ever.