Midras Kejadian 45:21: Midrash Tanchuma Buber & Bereshit Rabbah

(Gen. 46:28:) NOW HE HAD SENT JUDAH AHEAD OF HIM UNTO JOSEPH TO TEACH BEFORE HIM.³⁹This interpretation is assumed in the midrash. What is the meaning of < TO TEACH BEFORE HIM >? R. Nehemiah said: To establish an academy for him where he would teach Torah so that the tribes might study Torah.⁴⁰Gen. R. 95:3; Tanh., Gen. 11:11; also Gen. R. 94:3. You know that this is so; < for >, when Joseph had left him, Jacob knew at what chapter he had left him because he had taught him. When Joseph's brothers came and said to him (in Gen. 44:26): JOSEPH IS STILL ALIVE < … > HIS HEART GREW FAINT, because he did not believe it, as stated (ibid.): FOR HE DID NOT BELIEVE THEM. Jacob recalled at what chapter Joseph had left him. He said to them: Did he give you a sign⁴¹Gk.: semeion. < indicating > at what chapter Joseph left me? Jacob said in his heart: I know that he left me at the chapter on the heifer ('GLH, i.e., Deut. 21:1-9). He said to them: Say at what chapter he left me, and I will believe you. Joseph also recalled at what chapter he had left him. What did Joseph do? He gave them wagons ('GLH in the singular), as stated (in Gen. 45:21): SO JOSEPH GAVE THEM WAGONS. < This verse is > to teach you that in every place that he went he was busy at Torah, just as his ancestors had been, even though the Torah had not yet been given. Ergo, it is written of Abraham (in Gen. 26:5): AND HE KEPT MY CHARGE: MY COMMANDMENTS, MY STATUTES, AND MY TORAHS. From where did Abraham learn the Torah? R. Simeon ben Johay says: < His > two kidneys became like two full vessels which spouted forth Torah. And where is it shown? Where it says so (in Ps. 16:17): EVEN IN THE NIGHTS MY KIDNEYS ADMONISH ME. R. Samuel bar Nahman said in the name of R. Jonathan ben Eleazar Ish haBirah: Our father Abraham even knew the eruvim of cooked foods.⁴²See above, 3:14; also 3:1. Thus it is stated (in Gen. 26:5): BECAUSE ('QB 'ShR) ABRAHAM HEEDED MY VOICE, < AND KEPT MY CHARGE >…. Now at the age of three Abraham recognized his Creator, as stated (through the first word of this verse): 'QB (with a numerical value of 172). Since all the days of Abraham were one hundred and seventy-five, from here (Gen. 26:5) you learn (by simple subtraction) that at the age of three he had recognized him and that he was even keeping the fine points of Torah. He also taught his children, as stated (in Gen. 18:19): FOR I HAVE CHOSEN HIM SO THAT HE MAY CHARGE < HIS CHILDREN AND HIS HOUSEHOLD AFTER HIM TO KEEP THE WAY OF THE LORD, TO PRACTICE RIGHTEOUSNESS AND JUSTICE >…. The Holy One said to him: You have taught your children Torah in this world, but in the world to come I in my glory will teach them the Torah, as stated (in Is. 54:13): AND ALL YOUR CHILDREN SHALL BE TAUGHT BY THE LORD, AND GREAT SHALL BE YOUR CHILDREN'S PROSPERITY.

Another matter, “he sent Judah before him.” Rabbi Ḥanina son of Rabbi Aḥa, and Rabbi Ḥanina, one said: To arrange a residence for him. And one said: To arrange an academy in which he would teach Torah matters and in which the tribes would study. Know that it is so; when Joseph departed from him, he knew at which chapter that he was teaching him he left him. When Joseph’s brothers came to him and said to him: “Joseph is still alive… his heart was faint [because he did not believe them]” (Genesis 45:26). He remembered at which chapter he left him, and said to himself: I know that it was at the chapter of the beheaded calf [egla arufa] that Joseph left me. He said to them: ‘If you know at what chapter Joseph left me, I will believe you.’ Joseph, too, knew at what chapter he left him. What did Joseph do? He gave them wagons [agalot], as it is stated: “Joseph gave them wagons by Pharaoh’s order” (Genesis 45:21). This is to teach you that everywhere Jacob would settle he would study Torah, just as his fathers would.
At this point, the Torah had not been given, but it is written of Abraham: “[Because Abraham heeded My voice,] and he kept My charge, [My commands, My decrees, and My Torahs]” (Genesis 26:5) – from where did Abraham learn the Torah? Rabban Shimon says: His two kidneys became like two jugs of water and they would gush Torah. From where is it derived that it is so? As it is stated: “Even on nights [my kidneys] instruct me” (Psalms 16:7). Rabbi Levi said: He studied Torah on his own, as it is stated: “The dissembler in his heart shall have his fill from his own ways, and a good man shall be satisfied from himself” (Proverbs 14:14). Rabbi Yonatan Sar HaBira said: Abraham knew even the joining of cooked foods, as it is stated: “Because Abraham heeded…” (Genesis 26:5).⁶The end of the verse mentions “My Torahs,” in plural, implying both the written and oral Torahs. The oral Torah includes even rabbinic laws, like the joining of cooked foods [eruv tavshilin]. The rabbis forbade cooking on a festival day for Shabbat unless one prepares two cooked items for Shabbat before the festival day (see Beitza 15b).
How old was Abraham when he recognized his Creator? He recognized his Creator at the age of forty-eight years old. Reish Lakish said: At the age of three years old, as “ekev” is written, the numerical value of ekev, and Abraham lived one hundred and seventy-five years.⁷The verse states “because [ekev] Abraham heeded My voice…” The numerical value of the word ekev is one hundred and seventy-two, implying that Abraham heeded God’s voice for one hundred and seventy-two years. You learn from this that at age three, he recognized his Creator. He would observe the details of the Torah and would teach his children, as it is stated: “For I have loved him, [so that he will command his children and his household after him and they will observe the way of the Lord]” (Genesis 18:19). The Holy One blessed be He said to him: ‘You taught your children in this world, but in the World to Come, I, in My glory, will teach all of you the Torah,’ as it is stated: “All your children will be students of the Lord” (Isaiah 54:13).