יְמֵֽי־שְׁנוֹתֵ֨ינוּ בָהֶ֥ם שִׁבְעִ֪ים שָׁנָ֡ה וְאִ֤ם בִּגְבוּרֹ֨ת ׀ שְׁמ֘וֹנִ֤ים שָׁנָ֗ה וְ֭רָהְבָּם עָמָ֣ל וָאָ֑וֶן כִּי־גָ֥ז חִ֝֗ישׁ וַנָּעֻֽפָה׃
우리의 년수가 칠십이요 강건하면 팔십이라도 그 년수의 자랑은 수고와 슬픔뿐이요 신속히 가니 우리가 날아가나이다
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.
Mishnah Yevamot
If a boy of the age of nine years and one day had intercourse with his sister-in-law, and after he had come of age he married another woman and then died, if he had not known the first woman after he had become of age, the first one must have halitzah but may not be taken in yibbum, while the second may either have halitzah or yibbum. Rabbi Shimon says: [the yavam] may perform yibbum with whichever one he wants, and he must perform halitzah for the other [woman]. [The same law applies] whether he is of the age of nine years and one day, or whether he is of the age of twenty years but had not produced two pubic hairs.