הַמַּשְׂבִּ֣יַע בַּטּ֣וֹב עֶדְיֵ֑ךְ תִּתְחַדֵּ֖שׁ כַּנֶּ֣שֶׁר נְעוּרָֽיְכִי׃
quem te supre de todo o bem, de sorte que a tua mocidade se renova como a da águia.
Rashi on Psalms
that your youth renews itself like the eagle Like this eagle, which renews its wings and feathers from year to year. There is a Midrash Aggadah about a kind of eagle that returns to its youth when it becomes old.