Midrash Tanchuma (Bereshis 1:11) says:
אר”ש בן יהוצדק למודין היו שבשעה שא”ל הקדוש ברוך הוא לאדם ארורה האדמה בעבורך בעצבון תאכלנה כל ימי חייך אמר אדם רבש”ע עד מתי, א”ל עד שיולד אדם מהול. כיון שנולד נח מהול מיד ידע למך ואמר ודאי זה ינחמנו וגו’.
Rabbi Shimon son of Yehotzadak said, we learned that at the time that The Holy One Blessed Be He said to Adam “Cursed is the ground for your sake, in toil you shall eat all the days of your life..”, Adam said, “Master of the world, until when?”, (Hashem said) “until a man is born circumcised.” Since Noach was born circumcised, immediately Lamech knew and said “Certainly this one will give us rest etc.”
Seth was also born circumcised (Midrash Tanchuma 9:7, other places).
Since Seth wasn’t born yet at the time of the curse, shouldn’t the curse have been lifted when he was born circumcised?
Answer:
This would seem to be an example of conflicting Medrashim, a somewhat common occurrence which reflects 2 opinions or in this case traditions as to whether Seth was born circumcised.
