Midrasch zu Bereschit 34:22

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).