Tosefta do Rodzaju 24:71

(Translated from the Ehrfurt manuscript:) Rabbi Nehorai says: I abandoned every trade in the world and taught my children only Torah, for they eat the reward of its labour in this world but the principal remains for them in the world to come, because every trade in the world only stands for a man in his youth when his strength is upon him, but if he becomes sick, old or has troubles, he will not be able to do work and in the end will die in famine. But Torah keeps him from all evil in his youth and gives him a future and hope in his old age. In his youth, what does it say? "Those who hope in God, He will exchange for him strength, make his limbs rise like eagles" (Yeshayahu 40:31). In his old age, what does it say? "In old age they produce fruit" (Tehilim 92:15). And so too you find regarding Avraham our father, who God blessed in his old age more than in his youth, as it is said, "The time came when Avraham was old, and God blessed Avraham with everything (ba-kol)" (Bereishit 24:1). Rabbi Meir says: [The blessing was] that he didn't have a daughter. Rabbi Yehudah says: That he had a daughter. Rabbi Elazar ha-Moda'i says: This is the large sangenon (a kind of magical precious stone) that was in the hand of Avraham our father. Rabbi Shimon ben Yohai says: This is the beautiful jewel that hung around the neck of Avraham our father, that any sick person who saw it would immediately be healed. When Avraham our father died, God took it and hung it in the daytime. A second thing [that was his reward]: that Esav didn't rebel during his [grandfather's] lifetime. A third thing: that Yishmael did teshuvah during his [father's] lifetime. Others say: Avraham had a daughter and her name was Bakol. God blessed him in his old age more than in his youth because he did the Torah before it came, as it is said, "Because Avraham heard My voice and kept My charge, My commands, My laws, My instructions (torot)" (Bereishit 26:5)—it doesn't say "My Torah" (in singular) but "My instructions" (in plural), this teaches that the words of Torah and the words of scribes were revealed to him.