Commentary for Kiddushin 86:7
האיש מקדש את בתו תנן התם נערה המאורסה היא ואביה מקבלין את גיטה אמר רבי יהודה אין שתי ידים זוכות כאחד אלא אביה מקבל את גיטה וכל שאין יכולה לשמור את גיטה אין יכולה להתגרש
And she who cannot take care of her Get<span class="x" onmousemove="('comment',' V. Glos.');"><sup>10</sup></span> cannot be divorced.<span class="x" onmousemove="('comment',' I.e., an idiot cannot be divorced, even by her father's acceptance of the deed. V. Git. (Sonc. ed.) p. 304. n. 7.');"><sup>11</sup></span> Resh Lakish said: Just as they differ in respect to divorce, so they differ in respect to kiddushin.
Daf Shevui to Kiddushin
The Talmud quotes a mishnah from Gittin. According to the first opinion, a betrothed girl who is between 12 and 12.5 years of age, a na’arah, can either receive her own get or her father can. R. Yehudah holds that only her father can receive the get. And if she is so young (or mentally incapacitated) that she cannot hold on to her get, then she cannot be divorced.
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