Midrasch zu Bereschit 25:31

(R. Jochanan) asked him: Hast thou never learnt to read the Shema', or the Tephillah, or the Grace after meals? He replied to him: No. He arose and (R. Jochanan) taught him the three (prayers). (Again) he sat down and wept. (R. Jochanan) said to him: My son, why dost thou weep? He replied: Because I desire to learn Torah. He (thereupon) taught him two rules (of the Law) every day of the week, and on the Sabbath (Eliezer) repeated them and assimilated them. He kept a fast for eight days without tasting anything until the odour of his mouth attracted the attention of R. Jochanan ben Ẓakkai, who directed him to withdraw from his presence. He sat down and wept. (R. Jochanan) said to him: My son, why dost thou weep? He rejoined: Because thou didst make me withdraw from thy presence just as a man makes his fellow withdraw, when the latter is afflicted with leprosy. (R. Jochanan) said to him: My son, just as || the odour of thy mouth has ascended before me, so may the savour of the statutes of the Torah ascend from thy mouth to Heaven. He said to him: My son! Whose son art thou? He replied: I am the son of Hyrḳanos. Then said (R. Jochanan): Art thou not the son of one of the great men of the world, and thou didst not tell me? By thy life! he continued, This day shalt thou eat with me. (Eliezer) answered: I have eaten already with my host. (R. Jochanan) asked: Who is thy host? He replied: R. Joshua ben Chananjah and R. José the Priest.

(Gen. 25:31:) THEN JACOB SAID: SELL ME YOUR BIRTHRIGHT FOR TODAY. He said to him: Are you requesting my birthright? Do you request my share in the world to come? He said to him: I do not know whether you have a share in the world to come, but sell me the birthright since it is public knowledge¹⁵Rt.: PRSM; cf. Gk.: parresia (“boldness of speech”). FOR TODAY. SELL… FOR TODAY (KYWM): R. Aha said: Whoever knows how to {reply} [calculate] properly, knows that Israel received < the birthright > in this world only for a thousand years, because a day (YWM) for the Holy One is a thousand years. It is so stated (in Ps. 90:4): FOR A THOUSAND YEARS < IN YOUR EYES ARE LIKE THE DAY (KYWM) WHICH IS YESTERDAY >.¹⁶The Israelites knew only a millennium of true independence. See also Gen. R. 63:13.