Midrash su Ecclesiaste 9:12

“Just as you do not know the path of the wind, or how the bones grow in the womb of one who is pregnant; so you will not know the work of God, who does everything” (Ecclesiastes 11:5).
“Just as you do not know” – there are seven matters obscured from people, and they are the day of death, the day of consolation, the profundity of judgment, how one profits, what is in the heart of another, what is in a woman’s pregnancy, and this kingdom of Edom, when it will fall. The day of death, from where is it derived? It is as it is stated: “Man [also] does not know his time” (Ecclesiastes 9:12). The day of consolation, from where is it derived? It is as it is stated: “I am the Lord; at its time I will hasten it” (Isaiah 60:22). The profundity of judgment, from where is it derived? It is as it is stated: “For judgment is God’s” (Deuteronomy 1:17). How one profits, from where is it derived? It is as it is stated: “This is the gift of God” (Ecclesiastes 5:18). What is in the heart of another, from where is it derived? It is as it is stated: “I am the Lord, who probes the heart” (Jeremiah 17:10). What is in a woman’s pregnancy, from where is it derived? It is as it is stated: “Or how the bones grow in the womb of one who is pregnant.” And this kingdom of Edom, when it will fall, from where is it derived? It is as it is stated: “For it is a day of vengeance in My heart” (Isaiah 63:4).

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).

R. Yishmael says: Scripture comes to teach you how he is judged, viz. (Koheleth 9:12) "For a man does not know his time, like fishes that are caught in a flimsy net and like birds that are caught in the snare. Like them men are snared in a time of evil (i.e., when their evil is visited upon them), when it falls upon them suddenly."