תִּכָּ֣תֶב זֹ֭את לְד֣וֹר אַחֲר֑וֹן וְעַ֥ם נִ֝בְרָ֗א יְהַלֶּל־יָֽהּ׃
Zapisze się to dla rodu potomnego, a lud odrodzony będzie chwalił Pana.
Beit Aharon
It is found in the Midrash: "Write this for the last generation; and a nation will be created that will praise the Lord" (Psalms 102:19) - since the Holy One, blessed be He, creates them as a new creature on Rosh Hashanah and Yom Kippur. So what is incumbent upon us to do? To take a citron (etrog) and a lulav and praise Him.