Reference for Gittin 66:5

או דלמא טעמא דרשב"ג משום דקסבר כל מלתא דמתעבדא באפי בי עשרה צריכא בי עשרה למישלפה והילכך אפילו כולכם נמי

Do we say that the reason of Rabban Simeon b. Gamaliel [for forbidding in the case where he did not say 'all of you'] is that in his opinion if part of an evidence is nullified the whole is nullilied,<span class="x" onmousemove="('comment',' And therefore if we allowed this harm would ensue, as the rest might sign when they had no right to do so. ');">⁵</span>

Jastrow