לָכֵ֛ן יֵדַ֥ע עַמִּ֖י שְׁמִ֑י לָכֵן֙ בַּיּ֣וֹם הַה֔וּא כִּֽי־אֲנִי־ה֥וּא הַֽמְדַבֵּ֖ר הִנֵּֽנִי׃
Rashi on Isaiah
My people shall know When I redeem them, they will recognize that My name is master, monarch, and ruler, as is its apparent meaning.
Ibn Ezra on Isaiah
Therefore my people shall know my name when I shall proclaim, Behold, it is I.
Rashi on Isaiah
therefore, on that day The day of their redemption, they will understand that I am He Who speaks, and behold, I have fulfilled the prophecy.