Mishnah, Kelim1:8 (in Danby's edition of the Mishnah, p. 606). There is more lenient teaching in the Midrash HaGadol (Be'shelach) where it was learnt from Moses who carried with him the bones of Joseph that persons defiled from the dead were permitted to enter the Court of the Israelites and of the Levites (Moses being a Levite), but not the Court of the Priests.
Aharon HaLevi, Sefer ha-Chinuch, section # 362, on Numbers 5:1–3; Flavius Josephus, The Works of Flavius Josephus. Translated by William Whiston, A.M. Auburn and Buffalo. John E. Beardsley: 1895, s.v. Antiquities 3.11.3. The Mishnah (Kereitot 2:1) mentions four persons designated as "lacking in the atonement" (Hebrew: מחוסרי כפרה), e.g. the leper, the man who had a repetitive and uncontrollable seminal flux, the woman who had a profuse menstrual flow of blood for several days beyond her period of natural purgation, the woman after childbirth (postpartum). Such people remain in a state of uncleanness until they have immersed and brought their sacrificial animals for atonement. Persons who are defiled by corpse uncleanness are similar to them, in that they, too, remain in a perpetual state of uncleanness until they can be sprinkled twice with the water of purification and immerse in a ritual bath (Sifrei on Numbers 5:1-3).
Meiri (2006). Daniel Bitton (ed.). Beit HaBechirah (Chiddushei ha-Meiri) (in Hebrew). Vol. 3. Jerusalem: Hamaor Institute. pp. 10–11. OCLC181631040., Mo'ed Ḳaṭan 5b, s.v. כבר ביארנו.
Adani, Samuel ben Joseph (1997). "Abridged principles of halacha (chapter 3)". Sefer Naḥalat Yosef (in Hebrew). Ramat-Gan: Makhon Nir David. p. 17a. OCLC31818927. (reprinted from Jerusalem editions, 1907, 1917 and 1988)
Meiri (2006). Daniel Bitton (ed.). Beit HaBechirah (Chiddushei ha-Meiri) (in Hebrew). Vol. 3. Jerusalem: Hamaor Institute. p. 11. OCLC181631040., Mo'ed Ḳaṭan 5b, s.v. כל אלו מטמאין באהל.
