כִּֽי־יִבְעַ֤ל בָּחוּר֙ בְּתוּלָ֔ה יִבְעָל֖וּךְ בָּנָ֑יִךְ וּמְשׂ֤וֹשׂ חָתָן֙ עַל־כַּלָּ֔ה יָשִׂ֥ישׂ עָלַ֖יִךְ אֱלֹהָֽיִךְ׃
Rashi on Isaiah
As a young man lives with a virgin, etc. As a young man lives with a virgin, so shall your children live in you [after Jonathan].
Ibn Ezra on Isaiah
So shall thy sons marry thee. This is a figurative expression for the kingdom will be restored to thee.