Commentary for Kiddushin 36:10

האי מאי בשלמא אירוסין מאירוסין שאני אלא נישואין מנישואין

[Then how say,] 'and both agree' etc. ; surely a man cannot sell his daughter to servitude after marriage! Then what can you answer: her own erusin differs from her father's?<span class="x" onmousemove="('comment',' When her father receives kiddushin on her behalf, he loses his authority to sell her subsequently. But when she herself receives it (as explained p. 84, n. 10, that she is betrothed in virtue of the labour she owes her master) , and thus receive the kiddushin - viz., the renunciation of her labour - herself, her father retains the right to sell her.');">¹⁸</span> Then even if you say that it effects nissu'in her own nissu'in differs from her father's. How now? As for erusin differing from erusin, that is well;<span class="x" onmousemove="('comment',' For she does not altogether pass out of her father's control after erusin, e.g., in respect of inheritance and annulment of vows (p. 83, n. 1) . Therefore it may be said that he loses the right to sell her only after he himself accepts kiddushin, but not after she does so by means of designation.');">¹⁹</span> but can nissu'in differ from nissu'in?<span class="x" onmousemove="('comment',' Since nissu'in completely frees her from her father's authority, it does not matter at whose instance it is effected.');">²⁰</span>

Daf Shevui to Kiddushin