Responsa for Shabbat 200:4

אביי אמר איצטריך סד"א ה"מ היכא דלא הוי ד' אמות אבל היכא דהוי ד' אמות אקופי מקפי ליה

But why [state] POOL twice? — One refers to summer, and the other to winter, and both are necessary. For if only one were stated, I would say: That is only in summer, when it is the practice of people to walk therein to cool themselves; but in winter [it is] not [so]. And if we were informed [this] of winter, [I would say that] because they are mudstained they do not object;<span class="x" onmousemove="('comment',' To wade through a pool. ');">⁷</span> but in summer [it is] not [so]. Abaye said, They are necessary: I might argue, That is only where it [the pool] is not four cubits [across]; but where it is four cubits [across], one goes round it.<span class="x" onmousemove="('comment',' Instead of wading through it; hence it is not public ground. Therefore it is stated twice, to show that this case too is included. ');">⁸</span> R. Ashi said; They are necessary: I might argue, That is only where it [the pool] is four [across];<span class="x" onmousemove="('comment',' Rashi adds cubits; but the masc. form [H] must refer to handbreadths. This reading is also more likely, as otherwise he would not say that if less than four one might step across it. — S. Strashun. ');">⁹</span>

Teshuvot Maharam

Teshuvot Maharam

Teshuvot Maharam

Teshuvot Maharam