Pesachim 30a-30b
Nullification of prohibitions: within homogeneous mixtures, heterogeneous mixtures, chametz and prohibited wine \u2022 Bread must be baked neutral, not containing dairy or meat, unless certain steps are taken \u2022 Does this prohibition apply to wines? \u2022 May one use an oven for meat then dairy? \u2022 When can earthenware be kashered? \u2022 Which cold use earthenware may not be used on Pesach? \u2022 When is chametz collateral permitted or prohibited?