Reference for Gittin 30:6
ולאפוקי מדרב חסדא
We learnt: [IF HE DECLARES.] 'THE WHOLE WAS WRITTEN IN MY PRESENCE BUT ONLY ONE WITNESS SIGNED IN MY PRESENCE', THE GET IS INVALID. What now about the other witness? Do we presume that there is no-one who attests his signature? That cannot be; for even where one [person declares] IT WAS WRITTEN IN MY PRESENCE' AND ANOTHER SAYS 'IT WAS SIGNED IN MY PRESENCE', in which case one testifies to the whole of the writing and the other to the whole of the signing [ — even in that case the Get] is invalid; how much more so then if only half [of the signing is attested]? No; this shows that the proper explanation is either that of Raba or of R. Ashi, and that R. Hisda's is to be excluded.<span class="x" onmousemove="('comment',' The Mishnah quoted above ('if he says the whole was written in my presence but only one witness signed in my presence') has just been shown to be superfluous, and we are therefore entitled to infer some lesson from it. That inference, however, should be restricted to a minimum, and therefore the opinions of Raba and R. Ashi are preferable to that of R. Hisda. ');"><sup>5</sup></span>