Parshas Chayei Sara
Highlights of a shiur by Rav Yosef Jacobowitz
.גֵּר וְתוֹשָׁב אָנֹכִי עִמָּכֶם תְּנוּ לִי אֲחֻזַּת קֶבֶר עִמָּכֶם וְאֶקְבְּרָה מֵתִי מִלְּפָנָי
I am a stranger and a resident among you; give me a grave property among you, that I might bury my dead from before me.
Avraham’s burial of Sara is the Torah’s first mention of kevura.
We have a mitzva to bury the dead. But what if, chas v’shalom, the full body isn’t present?
Tosfos Yom Tov (Shabbos 10:5) maintains that a kezayis-sized piece of tissue is certainly subject to the mitzva, and a smaller part might be as well.
The Mishneh Lamelech and the Tiferes Yisrael (ibid.) challenge this from a Yerushalmi (Nazir 7:1) that says that although a nazir and a kohen must become tamei to bury a mes mitzva, that only applies if rosho v’rubo of the mes mitzva is present.
The Minchas Chinuch and other acharonim answer simply that this minimum applies only to the heter of mes mitzva to a kohen and a nazir, not to the mitzva of kevura per se.
The Noda Bihuda (Kama Y.D. 90) says that sevara dictates that a part smaller than rosho v’rubo is subject to bizayon hameis, so the mitzva of kevura applies. R’ Moshe (Y.D. 2:150) rules accordingly.
Rav Tokachinsky in Gesher Hachayim (16:2) states that even those who argue with the Tosfos Yom Tov would agree that if rosho v’rubo are present, all of it must be buried, not just enough that what remains is below the rosho v’rubo threshold.