Musar for Niddah 45:50
לא תיבדק לרבנן דאמרי קריא וקיפופא אין שאר עופות לא
— Some part is missing<span class="x" onmousemove="('comment',' In R. Hanina's statement. ');"><sup>40</sup></span>
Orchot Tzadikim
And a man should not rejoice to the point of hilarity for now all joy should be mixed with sobriety, for when our "Holy Rabbi" (Rabbi Judah the Prince) used to laugh thus, troubles came to the world (Berakoth 31a). And similarly "Rabbi Jeremiah would bring Rabbi Zera to the point of laughter, but Rabbi Zera did not laugh" (Niddah 23a).
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