Quotation for Pesachim 215:7
ולא פליגי הא בתרתי כסי קמאי הא בתרתי כסי בתראי אמרי לה להאי גיסא ואמרי לה להאי גיסא אמרי לה להאי גיסא תרי כסי קמאי בעו הסיבה דהשתא הוא דקא מתחלא לה חירות תרי כסי בתראי לא בעו הסיבה מאי דהוה הוה
It was stated: [For the eating of] the unleavened bread reclining is necessary; for the bitter herbs reclining is not necessary.<span class="x" onmousemove="('comment',' the former symbolizes freedom; the latter, bondage. Bitter herbs may not be eaten while reclining.');"><sup>8</sup></span> [As for the drinking of] the wine, - It was stated in R'Nahman's name [that] reclining is necessary, and it was stated in R'Nahman's name that reclining is not necessary.
Tosafot on Sukkah
It seems from here that women are exempt from reciting Hallel on Sukkos and Shavuos because it is a time-bound positive mitzvah. Although the Gemara implies that women are obligated in the four cups of wine on the first nights of Pesach, and the rabbis ostensibly only instituted the four cups to enhance the recitation of Hallel and Maggid, Hallel of Pesach is different because it commemorates the miracle and [women] also were part of the miracle.
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