Reference for Gittin 57:16
מאי בינייהו איכא בינייהו שליח מתנה ובפלוגתא דרב ושמואל רב אמר מתנה אינה כגט ושמואל אמר מתנה הרי היא כגט:
Said R. Johanan to him: This even schoolchildren know. What we should say is that sometimes [if the bearer did send the Get on by another bearer] the Get itself is no Get, because he puts himself in the same position as the bearer who was told by the husband not to divorce the wife except in the lower room and he divorced her in the upper room, or who was told not to divorce her except with the right hand and he divorced her with the left. Now both authorities are agreed that where she goes out to meet him [the second bearer] and gives him the article and then takes from him the Get, it is a perfectly valid Get.<span class="x" onmousemove="('comment',' [Although the husband may not approve of his pledge being in the possession of a third party, the Get is not invalidated since there has been no departure from the husband's instructions in regard to the delivery of the Get itself.] ');"><sup>12</sup></span>