In the scriptural instructions regarding annual festivals, the Feast of Unleavened Bread is clearly defined as lasting seven days, concluding on Abib/Nisan 21. This is evident in multiple passages such as Exodus 12:1-20, Leviticus 23:5-6, 8, and Numbers 28:16-25, which establish that the Feast of Unleavened Bread begins on Abib/Nisan 15 and extends until Abib/Nisan 21, marking a total of seven days during which unleavened bread must be eaten.

The 21st of Abib, also known as Nisan, holds significance as a holy feast day within the context of the Days of Unleavened Bread. It is the seventh day of these observances, marked as an annual Sabbath and referred to as a high day, a term still used by Jewish people today. This day concludes the seven days of eating unleavened bread, which begin on the 15th of Abib, following the Passover on the 14th of Abib.

The seventh day of Unleavened Bread, falling on Abib/Nisan 21, holds significant importance as a designated holy convocation. Scripture explicitly states that on this day, no servile work is to be done, strongly indicating that it is a Sabbath festival. According to Exodus 12:18, the eating of unleavened bread continues until the evening of the 21st, marked by the term ba erev, which denotes the end of the day. This sets the boundary for the Days of Unleavened Bread, spanning from the end of the 14th to the end of the 21st, encompassing the full seven days without including the 14th Passover. The use of ba erev in this context, as a general term for evening or night, contrasts with the more specific ben ha arbayim, ensuring clarity that the period of Unleavened Bread concludes at the close of Abib/Nisan 21.