Until the one and twentieth day, inclusively. For otherwise they were obliged to eat unleavened bread eight days, viz. on the day of the passover, Exodus 12:8, and seven days after, which is strictly and properly called the feast of unleavened bread, because in them they were tied to that ceremony only, except the two days of a holy convocation.
Related Commentaries of Exodus 12:18
Exodus 12:18
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.