Reference for Shabbat 105:15
לא בקטנים ומשום צער דיקא נמי דקתני
and the bell at the neck must be stopped up,<span class="x" onmousemove="('comment',' With cotton, wool, etc., to prevent if from ringing, which is forbidden on the Sabbath. ');"><sup>27</sup></span> and it may then amble about with it in the courtyard.<span class="x" onmousemove="('comment',' But not in the street, v. infra 54b. ');"><sup>28</sup></span> At all events it is stated, nor may foals [be led out] into the street with fodder-bags around their mouths': thus only into the street is it forbidden, but in a courtyard it is well [permitted]. Now, does this not refer to large [foals], its purpose being [the animals' greater] pleasure?<span class="x" onmousemove="('comment',' Though they can stretch their necks and eat from the ground. This contradicts Samuel. ');"><sup>29</sup></span> — No: it refers to small ones, the purpose being [to obviate] suffering.<span class="x" onmousemove="('comment',' It is difficult for very young foals to eat from the ground. ');"><sup>30</sup></span> This may be proved too, because it is taught