Arakhin 32A

מדאיצטריך ליה להלל לתקוני נתינה בעל כרחו הויא נתינה, הא בעלמא נתינה בעל כרחו לא הויא נתינה.

The Talmud elaborates: From the fact that it was necessary for Hillel to institute that giving against the will of the receiver is considered giving, in the case of houses of walled cities, one may infer that in general, giving against the will of the recipient is not considered giving.

מתקיף לה רב פפא, ואיתימא רב אשי: ודילמא כי איצטריכא ליה להלל לתקוני שלא בפניו, אבל בפניו ⁠— בין מדעתו בין בעל כרחו הויא מתנה!

Rav Pappa objects to this, and some say that it was Rav Ashi who objected: But perhaps when it was necessary for Hillel to institute this ordinance, it was specifically for a case where the seller gives the money not in the presence of the buyer; but if he repays the buyer in his presence, then whether the buyer was repaid with his consent or whether it was against his will, it is considered a valid act of giving.

איכא דאמרי, אמר רבא: מתקנתו של הלל ⁠— ״הרי זה גיטיך על מנת שתתני לי מאתים זוז״, ונתנה לו, בין מדעתו בין בעל כרחו ⁠— הויא נתינה. וכי איצטריך ליה להלל לתקוני ⁠— שלא בפניו, אבל בפניו ⁠— בין מדעתו בין בעל כרחו הויא נתינה.

There are those who say an opposite version of this discussion, i.e., that Rava says: One may infer from the ordinance of Hillel that if one says to his wife: This is your bill of divorce on the condition that you will give me 200 dinars, and she gave it to him, whether it was with his consent or whether it was against his will, it is a valid act of giving. And this is because when it was necessary for Hillel to institute this ordinance, it was specifically for a case where the seller gives the money not in the presence of the buyer. But if the seller repays him in his presence, whether the buyer was repaid with his consent or whether it was against his will, it is considered a valid act of giving.