(Exodus 12:19) "Seven days se'or (leavening) shall not be found in your houses": This tells me only (that the transgression) against finding (it). Whence do I derive (the same for) seeing? From (Ibid. 13:7) "And se'or shall not be seen unto you in all of your boundaries." This tells me that only se'or is subject to the injunctions against being seen and being found. Whence do we derive (the same for) chametz? It is written (Ibid.) "Chametz shall not be seen unto you, and se'or shall not be seen unto you." Se'or is likened to chametz, and chametz to se'or. Just as the first (se'or) is subject to both, so, the second. Just as the second (chametz) is of the five species (of grain [see above]), so, the first.