15 Seven days shall ye eat unleavened bread; even the first day ye shall put away leaven out of your houses: for whosoever eateth leavened bread from the first day until the seventh day, that soul shall be cut off from Israel.

17 And ye shall observe the feast of unleavened bread; for in this selfsame day have I brought your armies out of the land of Egypt: therefore shall ye observe this day in your generations by an ordinance for ever.

18 In the first month, on the fourteenth day of the month at even, ye shall eat unleavened bread, until the one and twentieth day of the month at even.

19 Seven days shall there be no leaven found in your houses: for whosoever eateth that which is leavened, even that soul shall be cut off from the congregation of Israel, whether he be a stranger, or born in the land.

20 Ye shall eat nothing leavened; in all your habitations shall ye eat unleavened bread.

God stressed multiple times the feast was to run for seven days. He said the feast was to run from the 14th day of the month to the 21st, that the bread was to be unleavened on the first day of the feast up through the seventh, and that the whole thing was to run for seven days. By describing His requirements for the duration in multiple ways, there could not be any chance of ambiguity or misunderstanding.

God also made repeatedly clear that the bread of the feast was to be unleavened, and if anyone violated this commandment it would be a grievous offense and they would be cast out of the community. He even instructed them to dispose of all the leaven in their homes, presumably so that no accidental consumption of it occurred.

I find myself wondering whether this example of God requiring the people to throw out the leaven was seen as a justification for the Pharisees to later “build a hedge” around the laws. By the time that Jesus was born, the spiritual leaders of Israel had added all manner of extra requirements around God’s laws, so as to further protect people from breaking the commandments. These “hedge laws” were often treated as if they were as sacred as God’s actual word, resulting in distraction and division from the truth faith, and Jesus had to spend much of his time correcting this matter. There is, of course, quite a difference between a buffer that is dictated by God and a buffer that is required by man.