Midrash su Genesi 34:15

Rabbi said: Isaac circumcised Jacob, and Esau; and Esau despised the covenant of circumcision just as he despised the birthright, as it is said, "So Esau despised his birthright" (Gen. 25:34). Jacob clung to the covenant of circumcision, and circumcised his sons and his grandsons. Whence (do we know) that the sons of Jacob were circumcised? Because it is said, "Only on this condition will the men consent unto us to dwell with us… if every male among us be circumcised, as they are circumcised." (Gen. 34:22). Another text says, "Only on this condition will we consent unto you: if ye will be as we be" (Gen. 34:15). Hence thou canst learn that the sons of Jacob were circumcised. The sons of Jacob circumcised their sons and their grandsons. They gave it to them as an inheritance for an everlasting statute, until Pharaoh the Wicked arose and decreed harsh laws concerning them, and withheld from them the covenant of circumcision. And on the day when the children of Israel went forth from Egypt all the people were circumcised, both young and old, as it is said, "For all the people that came out were circumcised" (Josh. 5:5).

"A man found him, and behold! He was blundering in the field: Rabbi Yannai said: He [Joseph] was met by three angels for scripture says, "A man found him" (Gen. 34:15); "and the man asked him"; and "the man said" (Gen. 34:17). "They have gone from here" - from the characteristics of the Place. "And they saw him far off"(Gen. 34:18): They said, 'Let us kill him by inciting the dogs against him.' "And they said one to another behold the dreamer comes"(Gen. 34:19): the rabbis said, “they exclaimed, Behold he is coming wrapped in his dreams”. Rabbi Levi said, “[they said] this one will ensnare us into serving foreign overloads.” "Come now therefore and let us slay him"(Gen. 34:20): The Holy One of Blessing said to them, “You say ‘We shall see’ and I say ‘We shall see’. Indeed "we shall see whose words will be fulfilled." (Jer. 34:28)