Reference

Leviticus 23:6

And on the fifteenth day of the same month is the feast of unleavened bread unto the Lord: seven days ye must eat unleavened bread.
4

These are the feasts of the Lord, even holy convocations, which ye shall proclaim in their seasons.

5

In the fourteenth day of the first month at even is the Lord’s passover.

6

And on the fifteenth day of the same month is the feast of unleavened bread unto the Lord: seven days ye must eat unleavened bread.

7

In the first day ye shall have an holy convocation: ye shall do no servile work therein.

8

But ye shall offer an offering made by fire unto the Lord seven days: in the seventh day is an holy convocation: ye shall do no servile work therein.

Counter-Arguments

The strongest case that this verse does not belong in this theme.

First Day of the Week

The verse specifies the "fifteenth day of the same month" and a duration of "seven days," but it makes no mention of "the first day of the week" or any weekly cycle.