English: “And the two kidneys” — not an animal with one kidney and not an animal with three kidneys (that is a blemish). “And the fat that is on them” — not the flesh that is on them (which is permitted to be eaten). “Which is on the loins” — this is the fat between the loin-sinews. These are the words of R’ Yossi HaGelili. R’ Akiva says: to include the fat on the coccyx.
In Sifra: The verse both defines the offered organs and delimits them. A one- or three-kidney animal is pasul as a blemish; only the peelable fat on the kidneys is taken, not the underlying flesh; and the phrase “on the loins” is the locus of a tannaitic expansion (loin-sinews vs coccyx).
Type of Learning
R’ Eliezer #1 (ריבוי) / scope of kidney-fat and loins language.
What Is Learned
Shelamim kidneys must be a normal pair; only their membrane fat is offered; the “loins” clause expands which adjacent fat layers join the altar portion.