Tazria, Siman 4 תזריע, ד׳
1 א

וּבִמְלֹאת יְמֵי טָהֳרָה וְגוֹ'. לָמָּה הִיא מְבִיאָה קָרְבָּן. אָמְרוּ רַבּוֹתֵינוּ זִכְרוֹנָם לִבְרָכָה: מֵאָה פְּעִיּוֹת הָאִשָּׁה פּוֹעָה, שֶׁנֶּאֱמַר: הֵן אַתֶּם מֵאַיִן וּפָעֳלְכֶם מֵאָפַע (ישעיה מא, כד). מַהוּ מֵאָפַע. מֵאָה פּוּעוֹת הִיא פּוֹעָה כְּשֶׁהִיא יוֹשֶׁבֶת עַל הַמַּשְׁבֵּר, תִּשְׁעִים וָתֵשַׁע לְמִיתָה, וְאַחַת לְחַיִּים. וְכֵיוָן שֶׁהַצָּרוֹת מַקִּיפוֹת אוֹתָהּ, הִיא נוֹדֶרֶת שֶׁלֹּא תִּזָּקֵק עוֹד לְאִישָׁהּ. לְפִיכָךְ מְבִיאָה קָרְבָּן, שֶׁנֶּאֱמַר: תָּבִיא כֶּבֶשׂ בֶּן שְׁנָתוֹ.

(Lev. 12:6:) “And when the days of her purification are fulfilled [for either a son or for a daughter, she shall bring a lamb in its first year for a burnt offering….]” Why does she bring an offering? Our masters have said, “She screams a hundred times when she sits on the birthing chair, as stated (Is. 41:24), ‘Behold you are like nothing, and your actions are less than zero.’ What is [the meaning of] ‘less than zero (me’effa)?’ There are one hundred screams (meah puot), ninety-nine for death and one for life.14Exod. R. 46:2; Lev. R. 27:7; Tanh., Lev. 8:11; PRK 9:6.h And when the pangs arrive for her, she vows that she will never favor her husband [with sexual intercourse] again. She therefore brings an offering,15Because of the impetuous oath. So Nid. 31:b. as stated (ibid.), ‘she shall bring a lamb in its first year.’”