And some of our teachers maintain another reason for this, that just as a woman who said "Give to my dog and I will be betrothed to you" or "Give upon the rock and I will be betrothed to you" and the rock is hers—when he gave, it is kiddushin, so too this ketannah is no less than a dog or a rock [Ra'avad and Ramban]. And even though there she said this to the one performing the kiddushin and here the father did not speak at all with the one performing the kiddushin, nevertheless, since he said to her "Accept your kiddushin," it is as if he said "Whoever gives to you, I consider it as if he gave to me," and this is as if he said to the one performing the kiddushin "Give to my daughter and she shall be betrothed to you." And this opinion maintains regarding the rock and the dog that by his giving upon the rock or to the dog she is betrothed to him by this alone, as is written in siman 30 section 26, see there; and they do not maintain as is written there in section 27 that he must afterwards give into her lap, for according to this opinion what benefit would her acceptance provide? And also this opinion does not maintain that the rock is by reason of chatzer as is written there and that the daughter is also by the law of chatzer, for if so, the father would need to stand at her side according to the law of chatzer, which requires that it be guarded by his knowledge or that he stand at the side of the chatzer [and see what I wrote in section 32]. Rather, they maintain the reason of arvut as is written there in section 28, that this is like "Give a maneh to so-and-so," see there, and here too they touched upon it from the law of arvut. According to this, even if he commanded the one performing the kiddushin to give to another ketannah who is not his daughter and that by this his daughter shall be betrothed to him—it would also be kiddushin [Beit Shmuel, subsection 7]. However, the reason of arvut would only suffice for kiddushin of money and not for kiddushin of a shetar, and indeed some say so, that this law applies only to kiddushin of money [see Ran, first chapter, starting with the words "He wrote"]. But there is another reason for this, that it is as if it reached his hand, and this is like what he said: "Whoever gives to you, I consider it as if he gave to me" [Beit Shmuel]. And most of the poskim do not maintain this reasoning [this is the approach of the Tosafot Rid, that even regarding a get this is effective in such a case; see Avnei Miluim, subsection 3, who also wrote thus, and one must further study the Beit Shmuel; and according to this opinion, indeed, this law does not apply to a shetar, and so it appears from the wording of the Ra'avad brought in the Rosh, first chapter, section 15, see there; but in the Baraita there, a shetar is also explicitly mentioned, and it seems to me that they maintain like the Tosafot Rid, and this is the difficulty of the Rosh there as the Ran wrote, and examine it closely].
ויש מרבותינו שסוברים בזה טעם אחר, דכמו אשה שאמרה "תן לכלב שלי ואתקדש לך" או "תן ע"ג הסלע ואתקדש לך" והסלע שלה – כשנתן הוי קדושין כמו כן הקטנה הזו לא גרעה מכלב וסלע [ראב"ד ורמב"ן], ואע"ג דשם אמרה זה להמקדש ובכאן הרי לא דיבר האב כלל עם המקדש, אמנם כיון שאמר לה "קבלי קדושך" הוה כמו שאמר "מי שיתן לך מנה מעלה אני עליו כאלו נתנם לי" וזהו כאלו אמר להמקדש "תן לבתי ותתקדש לך". ודיעה זו ס"ל בסלע וכלב דבנתינתו על הסלע או להכלב מקודשת לו בזה בלבד כמ"ש בסי' ל' סעי' כ"ו ע"ש, ולא ס"ל כמ"ש שם בסעי' כ"ז דצריך ליתן אח"כ לתוך חיקה, דלדיעה זו מאי מהני קבלתה, וגם לא ס"ל דיעה זו דסלע הוא מטעם חצר כמ"ש שם וגם הבת הוי מתורת חצר, דא"כ צריך האב לעמוד בצדה כדין חצר שצריך שישתמר לדעתו או שיעמוד בצד החצר [ועמ"ש בסעי' ל"ב], אלא דס"ל טעם ערבות כמ"ש שם סעי' כ"ח, דזהו כ"תן מנה לפלוני" ע"ש, וה"נ מדין ערבות נגעו בה, ולפי"ז אף אם צוה להמקדש ליתן לקטנה אחרת שאינה בתו ושבזה תתקדש בתו לו – ג"כ הוה קדושין [ב"ש סק"ז]. אמנם טעם הערבות לא יספיק רק לקדושי כסף ולא לקדושי שטר, ובאמת י"א כן דדין זה אינו אלא בקדושי כסף [ע' ר"ן פ"ק בד"ה כתב], אבל יש בזה טעם אחר דהוי כאלו הגיע לידו וזהו כמו שאמר "מי שיתן לך מעלה אני עליו כאלו נתן לי" [ב"ש], ורוב הפוסקים לא ס"ל סברא זו [זהו שיטת תוס' רי"ד דגם בגט מהני כה"ג, ע' אבנ"מ סק"ג שכתב ג"כ כן, וצ"ע על הב"ש ולדיעה זו באמת אין דין זה בשטר, וכ"מ מלשון הראב"ד שהובא ברא"ש פ"ק סט"ו ע"ש, אך בהברייתא מפורש שם גם שטר, ונ"ל דס"ל כתוס' רי"ד, וזהו קושית הרא"ש שם כמ"ש הר"ן, ודו"ק].