Responsa for Yevamot 214:12

בית שמאי אומרים תמאן וכו': והא מיאנה חדא זימנא אמר שמואל עד שתגדיל ותאמר רוצה אני במיאונים הראשונים

it is obvious that [the minor] was married to him;<span class="x" onmousemove="('comment',' Not merely betrothed. Before marriage, even if betrothal had taken place, a husband is not entitled to the usufruct of his wife's melog property. ');">³³</span> but [if this was the case] did not Beth Shammai rule [it may be asked] that a married minor may not exercise the right of refusal!<span class="x" onmousemove="('comment',' How then could she here at all make such a declaration! ');">³⁴</span> They bound him with two bonds.<span class="x" onmousemove="('comment',' Metaph. He was subjected to two penalties. [H] sing. [H] (Heb. [H]) 'knot', 'bond'. ');">³⁵</span> BETH SHAMMAI RULED:&nbsp;… BEFORE <i>BETH DIN</i> etc. Elsewhere we learned: <i>Halizah</i> and declarations of <i>mi'un</i> [must be witnessed by] three men.<span class="x" onmousemove="('comment',' Supra 101b, Sanh. 2a. ');">³⁶</span>

Teshuvot Maharam