Reference for Eruvin 47:2

אלא אי איתמר הכי איתמר הא מיעוטא שרי אמר רב הונא בריה דרב יהושע לא אמרן אלא דלא הוי בית סאתים אבל בית סאתים אסור

- The fact, however, is that if the statement has at all been made it must have been in the following terms: But<span class="x" onmousemove="('comment',' Since the prohibition was laid down in connection with a karpaf, the greater part of which was sown.');">⁴</span> [it follows that] if its less part [only was sown, the movement of objects within it] is permitted. Said R'Huna son of R'Joshua, this applies only [where the sown area was] less than two beth se'ah<span class="x" onmousemove="('comment',' So that it was not of sufficient importance to be given a status of its own.');">⁵</span>

Jastrow