Beitzah 18: The Prohibited Dunking of Yom Tov
Immersing a vessel on Shabbat - a problem of carrying. But what if the immersion was possible in one's own courtyard? Or what about on yom tov, when carrying isn't an issue? Abaye probes all the possibilities, and permutations of the prohibition. Also, suggestions why dunking on yom tov would be prohibited, in its own right. Plus, another instance of ho'il, since.