Pesahim 55a and Pesahim 55b, what counts as yuhara, taking on the airs of a more impressive Jew than one is; work on the morning of the 14th (or even the night before!) as custom or prohibition, as a matter of starting the work or even finishing, kinds of loss that might allow such work on the 14th or even Hol Ha-Moed, the middle days of a holiday, and then the people of Yeriho and their questionable practices.
