Hullin, Chapter Seven, Mishnah Three
1) If a person ate an olives bulk of the sciatic nerve, he incurs forty stripes.
2) If he ate all of it and it was not as much as an olive’s bulk, he is liable.
3) If he ate an olives bulk of it from one thigh and another olives bulk of it from the other thigh, he incurs eighty stripes.
a) Rabbi Judah says: he incurs only forty stripes.
Section one: As with many food prohibitions, one is not liable unless he eats an amount equivalent to an olive. While eating less is certainly prohibited, one who does so is not liable for the forty lashes, the punishment for transgression of a negative commandment.
Section two: If one eats the entire nerve, he is liable even if it is less than an olive.
Section three: According to the first opinion, the nerve of each thigh is a separate prohibition. Therefore, if one eats an olives bulk from each thigh, he is liable for eighty lashes (ouch!).
Rabbi Judah holds that only the sciatic nerve of only one of the thighs is prohibited, because, after all, Jacob was injured on only one of his legs. Most hold, according to Rabbi Judah, that it is the right thigh that is prohibited. In any case, one who eats both thighs is obligated for only forty lashes.