Midrash su Deuteronomio 21:1

7) (Vayikra 7:24) "lo tochluhu": I might think this means that he shall not feed it to others (non-Jews). It is, therefore, written (Vayikra 7:24) "ve'achol" — You may feed it to others. But perhaps "ve'achol" signifies that cheilev from which benefit may be derived is clean (of neveilah-tumah and may be used for all service), but the cheilev of an ox that was stoned, and that of an eglah arufah (the heifer of the broken neck, Devarim 21:1-9, [if it died before its mitzvah was performed]), from which benefit may not be derived, is not clean (of neveilah-tumah). It is, therefore, written (Devarim 21:9) (the redundant) "and the cheilev … and the cheilev" (to include the cheilev of the foregoing as permitted for all use).

And he sent Judah before him (Gen. 46:28). Jacob sent Judah before him to establish an academy wherein he might teach the Torah as he had previously done for the tribes. You know that he taught his sons earlier from the fact that Jacob remembered the chapter of the Torah that Joseph was studying with him at the time of his disappearance. When Joseph’s brothers returned and told him: “Joseph is yet alive” … his heart fainted, for he believed them not (Gen. 45:26). Jacob recalled the chapter of the Torah that Joseph was studying at the time of his departure, and he said to himself: “I know that he was studying the portion devoted to the beheaded heifer.”¹³See Deut. 21:1–9. Whereupon he turned to them and said: “If he gave you something to indicate the chapter he was studying when he departed from here, I will believe you.” Joseph had also remembered the chapter he was studying when he was separated from his father. What did Joseph do? He gave them wagons (ibid., v. 21). When Jacob saw the wagons (‘agalot), the spirit of their father revived forthwith.¹⁴Word-play relating ‘agalot (“wagons”) to kelayot (“kidneys”), stated in the next paragraph to be the organ through which Abraham learned and retained the law. This teaches us that wherever Joseph went, he devoted himself to the law, as his ancestors had done before him, even though the Torah itself had not yet been given. And thus it is written: Because that Abraham hearkened to My voice and kept My laws (Gen. 26:5).

(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.