Reference for Moed Katan 37:11

מ"ט ימים לא בטלו שאם לא גילח ערב הרגל אסור לגלח אחר הרגל

RABBAN GAMALIEL SAYS, NEW YEAR AND THE DAY OF ATONEMENT ARE [RECKONED] AS FESTIVALS; WHILE THE SAGES SAY, [THE RULE IS] NEITHER ACCORDING TO THE STATEMENT OF THE ONE NOR ACCORDING TO THE STATEMENT OF THE OTHER, BUT AZERETH IS [RECKONED] LIKE [THE OTHER] FESTIVALS AND NEW YEAR AND THE DAY OF ATONEMENT ARE [RECKONED] AS A SABBATH [DAY]. <big><b>GEMARA: </b></big>[THE RESTRICTIONS. FALL AWAY]. Said Rab, [this means only] 'the restrictions'<span class="x" onmousemove="('comment',' I.e., only the outer, formal observances of mourning but not the obligation.');">¹⁶</span> fall away, but the days [of mourning] do not fall away<span class="x" onmousemove="('comment',' I.e., the period of mourning of seven or (down to) thirty days (as the case may be, according to the wording of the Mishnah) is not canceled but only deferred pending the festive time.');">¹⁷</span> and so said also R'Huna:<span class="x" onmousemove="('comment',' Rab's disciple and his successor at the Academy of Sura.');">¹⁸</span> The 'restrictions fall away but the 'days' do not fall away; and R'Shesheth<span class="x" onmousemove="('comment',' Var. lec., Samuel; v. D.S. a.l.');">¹⁹</span> said that even the days also fall away.<span class="x" onmousemove="('comment',' I.e., they are not to be compensated after the festival to the number of the days during which the mourning formalities were suspended.');">²⁰</span> What is the meaning of, 'But the days [of mourning] do not fall away'? [It means] that if he had not cropped his hair on the day before the festival he is forbidden to crop himself after the festival

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