Halakhah su Giobbe 15:7

From the laws of the commandment is that which they, may their memory be blessed, said (Pesachim 11b) that we eat chamets all [the first] four hours of this day, and we suspend [it] all of the fifth - meaning to say that we do not eat [it], due to the decree because of a cloudy day, and we do not burn [it], but rather we [can] benefit from it, to feed it to any creature or to sell it to a person - and we burn it at the beginning of the sixth hour. And this is an ordinance of the Sages regarding the commandment, in order to distance a person from sin, so that he will not stumble to eat it at the beginning of the seventh hour - which is a Torah prohibition, as we have said. And [it is] also like they, may their memory be blessed expounded from another verse; as they said there in Pesachim 4b, "It is is written (Exodus 12:19), 'Seven days leaven, etc.,' yet it is [also] written (Exodus 12:15), 'but on the first day, etc.' Behold, how is this? [It is] to include the fourteenth day for destruction [of chamets]." And [so] the understanding of "first" (rishon) would be like [its usage], "Were you born rishon Adam" (Job 15:7), the understanding of which is before. And from that which the verse obligated to dispose of it on that day, we knew that part of that day would necessarily be permitted, as it is impossible to determine the exact first instant of a day and dispose of it then. And since it is like this: That part of the day is permitted, and Scripture did not elucidate which part of it is permissible, we divided it equally from true logic - as if you divide in [any] other way, there will be no foundation to the thing at all. And that is what they said over there, "[The word,] 'but (akh),' divides." And those that explained that akh is chats (divide) in [the letter susbtitution pattern called], "achs, betaa" did not understand the words of the Sages. [This] and the rest of the details of the commandment are in Tractate Pesachim in the first chapter.