Mistaking One Forbidden Thing for Another and a Father's Offering

Rabbi Shimon Shezuri says: they did not dispute about a case involving a single prohibition, that he is liable. About what did they dispute? About a case involving two distinct prohibitions, where Rabbi Eliezer obligates a sin-offering and Rabbi Yehoshua exempts. Rabbi Yehuda says: even in a case of a single prohibition Rabbi Yehoshua would exempt him. How so? His two wives were menstruant and his two sisters were with him in the house, and he intended to lie with this one but lay with that one. Figs and grapes lay before him and he intended to pick figs but picked grapes, or grapes but picked figs, or black ones but picked white, or white but picked black; Rabbi Eliezer obligates a sin-offering and Rabbi Yehoshua exempts. I am astonished if Rabbi Yehoshua would exempt in such a case; if so, why is it said "in it"? To exclude one who acts without intent. "And he shall bring" (Leviticus 4:23) means even after the Day of Atonement. "His offering" means he discharges his obligation with his own offering and not with his father's offering. One might think he cannot discharge it with his father's offering that the father set aside from a lighter category for a graver one or from a graver for a lighter, but that he can discharge it with an offering the father set aside from a lighter for a lighter or from a graver for a graver; therefore Scripture teaches "his offering," he discharges it with his own and not with his father's. One might think he cannot discharge it with an animal his father set aside even from lighter to lighter or graver to graver, since a man cannot complete his naziriteship by shaving over his father's animal, but he can discharge it with money his father set aside, even from graver to lighter or lighter to graver, since a man may complete his naziriteship over his father's money when it is unspecified though not when it is specified; therefore Scripture teaches "his offering," he discharges it with his own and not with his father's. One might think he cannot discharge it even with money he himself set aside from lighter to lighter or graver to graver, but that he can discharge it with an offering he set aside for himself from lighter to lighter and graver to graver; therefore Scripture teaches "his offering... for his sin," his offering must be for the sake of his particular sin. One might think he cannot discharge it with an animal he set aside for himself from lighter to graver and graver to lighter and lighter to lighter and graver to graver, since if he set aside an animal for the matter of forbidden fat and brought it for blood, or for blood and brought it for fat, he has not misappropriated and has not atoned; but he can discharge it with money he set aside for himself across these categories, since if he set aside money for forbidden fat and brought it for blood, or for blood and brought it for fat, he has misappropriated and has atoned; therefore Scripture teaches (below, verse 35) "for his sin," his offering must be for the sake of his particular sin.