בַּיּ֣וֹם הַה֗וּא יִהְיֶ֤ה יִשְׂרָאֵל֙ שְׁלִ֣ישִׁיָּ֔ה לְמִצְרַ֖יִם וּלְאַשּׁ֑וּר בְּרָכָ֖ה בְּקֶ֥רֶב הָאָֽרֶץ׃
In that day shall Israel be the third with Egypt and with Assyria, a blessing in the midst of the earth;
Read kabbalistic (mystical) interpretation of Isaiah 19:24: and classical mystical sources.