以賽亞書 40:31 猶太思想：Akeidat Yitzchak & Duties

The meaning of our opening aggadah is as follows. If you refrain from contact with your wife during the seven days of the menstrual cycle, tum-ah, you will merit the blessing of the eighth day, i.e. circumcision, which symbolises ascendancy over the spirit of impurity, attainment of purity. Since "seven days" represent the "creation cycle," the number seven always reminds man both of his duties and of his limitations on this planet.

(6) The alchemist is not immune from sickness and disease which hinders his joy in being wealthy, and prevents him from benefiting from what he has and enjoying what he has acquired. But one who trusts in G-d, is immune from sickness and disease except as an atonement or to increase his reward, as written "Now youths shall become tired and weary, and young men shall stumble" (Yeshaya 40:30), "those who hope in G-d will renew strength" (Yeshaya 40:31), and "For the arms of the wicked shall be broken, but the L-ord supports the righteous" (Tehilim 37:17).