Musar for Shabbat 106:15
ואיבעית אימא הא והא ר' יהודה ולא קשיא כאן ליבש כאן ליחלב
within his tehum.<span class="x" onmousemove="('comment',' When an animal is entrusted to a cowherd, its tehum is that of the cowherd, i.e., it may go only where the cowherd may go. Here the owner's tehum stretched beyond that of the cowherd; hence he may call the animal that strayed beyond its own tehum, for even if he forgets himself and goes for it, he is still within his own boundaries. Nevertheless he may not actually go for it, because when one (a man or a beast) goes beyond his tehum, he becomes tied to that spot and may only move within a radius of four cubits from it; hence the owner must not actually lead the animal away, but may only call it. (One can extend his tehum by placing some food at any spot within the two thousand cubits, whereupon he may then walk a further two thousand cubits from that spot. Here the owner had extended his tehum, but not the cowherd). ');"><sup>14</sup></span>