Pesahim 71a and Pesahim 71b, when the simha offering must be given to qualify as simha for the holiday (and which days of the holiday obligate simha), when the fats of a hagiga must be offered (and whether the word boker means the first morning), and then on to a new Mishnah, on to’eh bi-dvar mitzvah, erroneously thinking one was doing a mitzvah.
