יח בַּיּוֹם הַהוּא יִהְיוּ חָמֵשׁ עָרִים בְּאֶרֶץ מִצְרַיִם מְדַבְּרוֹת שְׂפַת כְּנַעַן וְנִשְׁבָּעוֹת לַיהוָה צְבָאוֹת עִיר הַהֶרֶס יֵאָמֵר לְאֶחָת׃
19:18 Speaking the language of Canaan
Yeshayahu prophesies that there will be five Egyptian cities that speak the language of Canaan and swear by Hashem’s name . According to Ramban (Exodus 30:13), the term “language of Canaan” refers to the Hebrew language, known in Jewish literature as Lashon HaKodesh (לשון הקודש), ‘the Holy Tongue,’ because it is the language with which God speaks to His prophets and His nation. After the Egyptians in these cities experience Hashem’s strength, they will be so moved to worship Him that they will learn the holy language and erect an altar on which to serve God. This will also represent a partial fulfillment of another of Yeshayahu’s prophecues, that in the future the whole world will be filled with knowledge of God (11:9).