בַּיָּמִ֣ים הָהֵ֔ם לֹא־יֹאמְר֣וּ ע֔וֹד אָב֖וֹת אָ֣כְלוּ בֹ֑סֶר וְשִׁנֵּ֥י בָנִ֖ים תִּקְהֶֽינָה׃
In those days they shall say no more: ‘The fathers have eaten sour grapes, And the children’s teeth are set on edge.’
Rashi on Jeremiah
unripe grapes A fruit that is not yet ripe, and it sets the teeth on edge.
Rashi on Jeremiah
And the teeth of the children shall be set on edge... The children for the fathers’ iniquity.