Halakhah к Шмот 12:4

That He prohibited an uncircumcised one from eating the priestly tithe. And the law is the same for other consecrated foods - that an uncircumcised one is forbidden to eat them. But this [prohibition of] eating is not made explicit in Scripture, but is rather learned from a verbal analogy. Yet the receivers [of the tradition] have explained that this prohibition is from the Torah. And the language of the Gemara, Yevamot (Yevamot 70a), is, "From where [do we know] that an uncircumcised one does not eat priestly tithe? It is stated, 'A sojourner (toshav) and a hired servant' (Exodus 12:45) with regard to the Pesach-offering; and [it is stated, 'a tenant (toshav) of a priest, or a hired servant, shall not eat of the consecrated food' (Leviticus 22:10),] with regard to priestly tithe. Just as 'a toshav and a hired servant,' stated with regard to the Pesach-offering, an uncircumcised one is forbidden from [eating] it; so too, 'a toshav and a hired servant,' stated with regard to priestly tithe, an uncircumcised one is forbidden from [eating] it." And the law is the same for other consecrated foods. And this is also the language of Sifra (Sifra, Emor, Chapter 4:18). And there they said, "Rabbi Akiva said, '"A man, a man" (Exodus 12:4), is to include the uncircumcised.'" And there - meaning in the Gemara, Yevamot - it is made clear that according to the Torah, one [whose circumcised foreskin is] pulled may eat of the priestly tithe. But [rabbinically], they decreed about him [that he may not eat of it], because he looks like one who is uncircumcised. Behold it has already been made clear to you that one uncircumcised is forbidden [to eat] priestly tithe, from the Torah; whereas one who is pulled is forbidden [rabbinically]. And understand this. And there, they said, "One pulled must get circumcised [rabbinically]." (See Parashat Emor; Mishneh Torah, Heave Offerings 7.)