פירוש על קידושין 37:9

Abaye also explains this baraita. If the original sale money was not given as kiddushin, then there still needs to be an act of kiddushin. This kiddushin happens when the master designates her to himself or her son. Like all regular acts of betrothal, this needs to be done with her consent.

R. Nahman b. Yitzchak says that even if the original sales money counts as kiddushin, we can still say that designation requires her consent. The Torah uses the word “ye’adah” in order to let us know that her consent is required. [Below we will see that R. Nahman b. Yitzchak himself holds that the original sales money does not count as kiddushin].