כִּ֣י יָגֹ֗רְתִּי מִפְּנֵ֤י הָאַף֙ וְהַ֣חֵמָ֔ה אֲשֶׁ֨ר קָצַ֧ף יְהוָ֛ה עֲלֵיכֶ֖ם לְהַשְׁמִ֣יד אֶתְכֶ֑ם וַיִּשְׁמַ֤ע יְהוָה֙ אֵלַ֔י גַּ֖ם בַּפַּ֥עַם הַהִֽוא׃
我因永恆者向你們大發烈怒、要消滅你們而十分懼怕；但那一次永恆者又應允了我。
Akeidat Yitzchak
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.