I have sworn by myself (comp. Genesis 22:17; Jeremiah 22:5; Jeremiah 49:15). "God swears "by himself," because he can swear by no greater" (Hebrews 6:13). He condescends, for man's sake, to confirm in this way promises that are exceedingly precious (see the Homiletics on Isaiah 14:24).
The word is gone out of my mouth in righteousness. So Dr. Kay and Mr. Cheyne (comp. Isaiah 45:19, "I the Lord speak righteousness"). And shall not return; i.e. shall not be withdrawn or retracted. God's gifts and promises are "without repentance."
Every knee shall bow, every tongue shall swear. This universal turning to God belongs to the final Messianic kingdom, prophesied in Isaiah 2:2-4; Isaiah 11:6-9; Isaiah 35:1-10; Isaiah 65:17-25; Isaiah 66:18-23; and also by Daniel (Daniel 7:9-14) and St.
John the Divine (Revelation 21:1-4). The entire destruction of God's enemies is to take place previously (Revelation 19:17-21).