אעָרֵב דְּבֵית דִּין הוּא דְּלָא בָּעֵי קִנְיָן, הָא בְּעָלְמָא בָּעֵי קִנְיָן.
It is only a guarantor who undertakes a loan guarantee in the presence of a court who does not require an act of acquisition; this indicates that generally, a guarantor requires an act of acquisition in order to be obligated to pay.
בוְהִלְכְתָא: עָרֵב בִּשְׁעַת מַתַּן מָעוֹת – לֹא בָּעֵי קִנְיָן, אַחַר מַתַּן מָעוֹת – בָּעֵי קִנְיָן. עָרֵב דְּבֵית דִּין – לָא בָּעֵי קִנְיָן; דִּבְהָהִיא הֲנָאָה דִּמְהֵימַן לֵיהּ – גָּמַר וּמְשַׁעְבֵּד לֵיהּ.
The Gemara concludes: And the halakha is that a guarantor who accepts responsibility for the loan at the time of the giving of the money does not require an act of acquisition; but if he accepts responsibility after the giving of the money, he requires an act of acquisition. Moreover, a guarantor who undertakes a loan guarantee in the presence of a court does not require an act of acquisition, as in return for that gratification that he experiences in that the court trusts him, he resolves to obligate himself.
גהֲדַרַן עֲלָךְ גֵּט פָּשׁוּט, וּסְלִיקָא לַהּ מַסֶּכֶת בָּבָא בָּתְרָא