Reference for Rosh Hashanah 18:6
מאי דבר אחר וכי תימא אי אפשר דליכא חד בסוף העולם דלא משלח זו מסורה לב"ד וזו אינה מסורה לב"ד
dismissing slaves, but it is not possible that there should be no [opportunity for] blowing the trumpet.<span class="x" onmousemove="('comment',' It is hardly possible that there should be no trumpet.');"><sup>9</sup></span> Another explanation is that the per formance of the latter depends on the Beth din, but the performance of the former does not depend on the Beth din.<span class="x" onmousemove="('comment',' Because the Beth din may not be able to compel all persons to dismiss their slaves.');"><sup>10</sup></span> What need is there for the alternative explanation? - Because you might argue that it is impossible that there should not be someone in some part of the world who has not a slave to dismiss.