יחזקאל מד:לא פירוש: רש״י

Anything that has died of itself or is fatally wounded, etc. Since nipping the neck of the bird sin- offering was permitted, which is [tantamount to] an animal that died of itself or was fatally wounded [since it is not the normal method of slaughter], he had to warn them concerning [eating] other creatures that died of themselves or were fatally wounded. So our Sages explain.