נִשְׁבַּ֛ע יְהוָ֥ה צְבָא֖וֹת לֵאמֹ֑ר אִם־לֹ֞א כַּאֲשֶׁ֤ר דִּמִּ֙יתִי֙ כֵּ֣ן הָיָ֔תָה וְכַאֲשֶׁ֥ר יָעַ֖צְתִּי הִ֥יא תָקֽוּם׃
The LORD of hosts hath sworn, saying: Surely as I have thought, so shall it come to pass; And as I have purposed, so shall it stand,
Rashi on Isaiah
as I thought concerning Assyria, so it was. You, Nebuchadnezzar, saw that the words of the prophets of Israel about Sennacherib were fulfilled.
Ibn Ezra on Isaiah
He hath sworn. The decree of God is His oath.26According to I. E. the unchangeable decree of the Lord is called His oath; it is an anthropomorphism.
Ibn Ezra on Isaiah
I thought. Whatever I had planned, as far as concerned the past, has come to pass, and the same will be the case concerning the events that are planned for the future.