זֹ֖את אֲשֶׁ֣ר לַלְוִיִּ֑ם מִבֶּן֩ חָמֵ֨שׁ וְעֶשְׂרִ֤ים שָׁנָה֙ וָמַ֔עְלָה יָבוֹא֙ לִצְבֹ֣א צָבָ֔א בַּעֲבֹדַ֖ת אֹ֥הֶל מוֹעֵֽד׃
“Inilah ketentuan bagi orang-orang Lewi: sejak berumur dua puluh lima tahun ke atas, setiap orang Lewi harus datang untuk bergabung dalam barisan yang bertugas pada pelayanan Kemah Pertemuan.
Pirkei Avot
He used to say: At five years of age the study of Scripture; At ten the study of Mishnah; At thirteen subject to the commandments; At fifteen the study of Talmud; At eighteen the bridal canopy; At twenty for pursuit [of livelihood]; At thirty the peak of strength; At forty wisdom; At fifty able to give counsel; At sixty old age; At seventy fullness of years; At eighty the age of “strength”; At ninety a bent body; At one hundred, as good as dead and gone completely out of the world.