מדרש אויף בראשית 36:22

R. Simlai stated: In reference to Reuben, it is written: And delivered him out of their hand (ibid. 37:2). Hence you learn that he was not responsible for the selling of Joseph. Similarly Judah said to them: What profit is it if we slay our brother? (ibid., v. 36). Now, inasmuch as these were the four eldest sons, it is apparent that Simeon and Levi must have been responsible for his sale. When they came to Egypt, Joseph looked angrily at Simeon, as it is said: And took Simeon from among them and bound him (ibid. 42:24). Hence he addressed them together: Simeon and Levi are brothers.

Our Rabbis were taught: (Num. 15, 30) "But the person that doth aught with a high hand; this refers to Menasseh b. Hezekiah who sat and lectured on topics with the object of fault-finding," saying, "Could not Moses have found something better than (Gen. 36, 22) "And Lotan's sister was Thimna, or, (Ib.) she was a concubine of Eliphaz b. Esau," or that of (Ib. 13, 14) "And Reuben went in the days of the wheat harvest and found mandrakes in the field." A heavenly voice was then heard saying (Ps. 50, 20) "Thou sittest and speakest against thy brother, against thy own mother's sons thou utterest slander, etc." And to him also applies the words of tradition: (Is. 5, 18) Wee unto those that draw iniquity with the cords of falsehood, and as with a wagon-rope, sinfulnesses." What does a wagon-rope mean? A. Assi said: "In the beginning, the evil inclination appears as thin as the thread of a spider's web; and finally he becomes as thick as a wagon rope." Since we have already arrived at it, let us see what does And Lotan's sister was Thimna really mean. Thimna was a princess, as it is written (Gen. 36, 40) Duke Thimna, and dukedom means a kingdom without a crown. She desired to become a proselyte, but Abraham, Isaac, and Jacob did not accept her. And she went and became the concubine of Eliphaz b. Esau, saying it is better to be a servant in this nation than to be a princess of another. And her offspring was Amalek, who troubled Israel as a punishment to their parents, who ought not to have driven her away.

“Timna was a concubine of Elifaz son of Esau, and she bore Amalek to Elifaz. These are the sons of Ada wife of Esau” (Genesis 36:12).
“Timna was a concubine of Elifaz son of Esau” – Rabbi Shimon ben Yoḥai taught: Why do I [need for the verse] to expound and say: “Timna was a concubine of Elifaz son of Esau”? It is to inform us of the praiseworthiness of the household of Abraham our patriarch, to what extent the kingdoms and realms wished to cleave to him. Who was Lotan? He was one of the rulers, as it is stated: “The chieftain of Lotan” (Genesis 36:29), and it is written: “Lotan’s sister was Timna” (Genesis 36:22). “Timna was a concubine…” She said: ‘Since I am not worthy to marry him as a wife, I will be his maidservant.’ The matters can be inferred a fortiori: If the wicked Esau, who had to his credit only one mitzva, because he honored his father, kingdoms and realms wish to cleave to him, all the more so that they would wish to cleave to the righteous Jacob, our patriarch, who fulfilled the Torah in its entirety.