"If he utterly refuse" (Exodus 22:16) comes to include the orphan girl for the fine, in a case where he came upon her and afterward she was orphaned. "He shall weigh out silver according to the bride-price of virgins" (Exodus 22:16) - that this should be like the bride-price of virgins, and the bride-price of virgins like this. From here they supported the marriage contract of a woman as deriving from the Torah; the words of Rabban Shimon ben Gamliel. But the Sages say: the marriage contract of a woman is not from the words of the Torah but from the words of the Scribes. Rabbi Akiva says: from where do we learn that the fine applies even if she was widowed, even if she was divorced? Reason supports it: since he is entitled to annul her vows and entitled to the money of her fine, and so on. "He shall surely endow her to be his wife" - why is this stated? Because it says, "and the man who lay with her shall give" (Deuteronomy 22:29). I might hear that just as with the seized woman he gives at once, so with the seduced woman he gives at once. Scripture states, "he shall surely endow her to be his wife," teaching that he establishes for her a bride-price, and a bride-price is nothing other than a marriage contract, as it is stated, "increase upon me greatly the bride-price and the gift" (Genesis 34:12). "He shall surely endow her to be his wife" - Scripture speaks of a woman fit for him, to exclude a widow to a high priest, a divorcee or a chalutzah to an ordinary priest, a mamzeret or a Gibeonite woman to an Israelite, an Israelite woman to a mamzer or a Gibeonite. "If he utterly refuse" teaches that if the father wishes, he may uphold the marriage, and if the father wishes, he may send her out. From where do I learn the seized woman? You may reason it out: since the seized woman is in her father's domain, and so on. If you have learned about the seduced woman that if the father wishes he upholds and if the father wishes he sends out, so too the seized woman: if the father wishes he upholds, if the father wishes he sends out. And further, by an a fortiori argument: if the seduced woman, where he acted only against her father's will, and so on. "He shall weigh out silver" - but we have not heard how much. I will reason: it says here "silver" and it says there "silver" (Deuteronomy 22:29); just as there it is fifty pieces of silver, so here it is fifty pieces of silver. "According to the bride-price of virgins" - this comes to teach and turns out to be itself taught: just as there it is fifty, and so on. "You shall not allow a sorceress to live" (Exodus 22:17) - this is written in remez 24 and in remez 182.
The Bride-Price of Fifty Shekels and the Roots of the Ketubah
Yalkut Shimoni on Torah 347:2
אִם מָאֵן יְמָאֵן, לְרַבּוֹת יְתוֹמָה לִקְנָס בְּבָא עָלֶיהָ וְאַחַר כָּךְ נִתְיַתְּמָה. כֶּסֶף יִשְׁקֹל כְּמֹהַר הַבְּתוּלֹת, שֶׁיְּהֵא זֶה כְּמֹהַר הַבְּתוּלוֹת, וּמֹהַר הַבְּתוּלוֹת כָּזֶה. מִכַּאן סָמְכוּ לִכְתֻבַּת אִשָּׁה מִן הַתּוֹרָה, דִּבְרֵי רַבַּן שִׁמְעוֹן בֶּן גַּמְלִיאֵל. וַחֲכָמִים אוֹמְרִים. כְּתֻבַּת אִשָּׁה אֵינָהּ מִדִּבְרֵי תוֹרָה, אֶלָּא מִדִּבְרֵי סוֹפְרִים. רַבִּי עֲקִיבָא אוֹמֵר, מִנַּיִן אֲפִלּוּ נִתְאַרְמְלָה אֲפִלּוּ נִתְגָּרְשָׁה, וְהַדִּין נוֹתֵן, הוֹאִיל וְרַשַּׁאי בַּהֲפָרַת נְדָרֶיהָ וְרַשַּׁאי בְּכֶסֶף קְנָסָהּ וְכוּ'. מָהֹר יִמְהָרֶנָּה לּוֹ לְאִשָּׁה, לָמָּה נֶאֱמַר, לְפִי שֶׁהוּא אוֹמֵר (דברים כב, כט) "וְנָתַן הָאִישׁ הַשֹּׁכֵב עִמָּהּ", שׁוֹמֵעַ אֲנִי כְּשֵׁם שֶׁבִּתְפוּסָה נוֹתֵן מִיַּד כָּךְ בִּמְפֻתָּה נוֹתֵן מִיָּד, תַּלְמוּד לוֹמַר מָהֹר יִמְהָרֶנָּה לּוֹ לְאִשָּׁה, מַגִּיד שֶׁהוּא עוֹשֶׂה עָלָיו מֹהַר, וְאֵין מֹהַר אֶלָּא כְּתֻבָּה, שֶׁנֶּאֱמַר "הַרְבּוּ עָלַי מְאֹד מֹהַר וּמַתָּן". מָהֹר יִמְהָרֶנָּה לּוֹ לְאִשָּׁה, בִּרְאוּיָה לוֹ, הַכָּתוּב מְדַבֵּר, לְהוֹצִיא אַלְמָנָה לְכֹהֵן גָּדוֹל, גְּרוּשָׁה וַחֲלוּצָה לְכֹהֵן הֶדְיוֹט, מַמְזֶרֶת וּנְתִינָה לְיִשְׂרָאֵל, בַּת יִשְׂרָאֵל לְמַמְזֵר וּלְנָתִין. אִם מָאֵן יְמָאֵן, מַגִּיד שֶׁאִם רָצָה הָאָב, יְקַיֵּם, וְאִם רָצָה הָאָב, יוֹצִיא. תְּפוּסָה מִנָּיִן, הֲרֵי אַתָּה דָן, הוֹאִיל וּתְפוּסָה בִּרְשׁוּת אָבִיהָ וְכוּ', אִם לָמַדְתָּ עַל הַמְּפֻתָּה שֶׁאִם רָצָה הָאָב יְקַיֵּם וְאִם רָצָה הָאָב יוֹצִיא, אַף תְּפוּסָה, רָצָה הָאָב יְקַיֵּם, רָצָה הָאָב יוֹצִיא. וְעוֹד קַל וָחֹמֶר, וּמָה אִם מְפֻתָּה, שֶׁלֹּא עָבַר אֶלָּא עַל דַּעַת אָבִיהָ וְכוּ'. כֶּסֶף יִשְׁקֹל, אֲבָל לֹא שָׁמַעְנוּ כַּמָּה, הֲרֵי אֲנִי דָן, נֶאֱמַר כָּאן כֶּסֶף וְנֶאֱמַר לְהַלָּן (דברים כב, כט) "כֶּסֶף", מַה לְּהַלָּן חֲמִשִּׁים כָּסֶף אַף כָּאן חֲמִשִּׁים כָּסֶף. כְּמֹהַר הַבְּתוּלֹת, הֲרֵי זֶה בָּא לְלַמֵּד וְנִמְצָא לָמֵד, מַה לְּהַלָּן חֲמִשִּׁים וְכוּ'. (שמות כב יז-יח) מְכַשֵּׁפָה לֹא תְחַיֶּה (כָּתוּב בְּרֶמֶז כ"ד, וּבְרֶמֶז קפ"ב).