Reference

Exodus 12:2

This month shall be unto you the beginning of months: it shall be the first month of the year to you.
1

And the Lord spake unto Moses and Aaron in the land of Egypt, saying,

2

This month shall be unto you the beginning of months: it shall be the first month of the year to you.

3

Speak ye unto all the congregation of Israel, saying, In the tenth day of this month they shall take to them every man a lamb, according to the house of their fathers, a lamb for an house:

4

And if the household be too little for the lamb, let him and his neighbour next unto his house take it according to the number of the souls; every man according to his eating shall make your count for the lamb.

Counter-Arguments

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

First Day of the Week

The verse explicitly refers to the "beginning of months" and "first month of the year," which are temporal units related to the calendar year, not the first day of the week. There is no mention of "day" or "week" in the text.