Reference

Mark 14:12

And the first day of unleavened bread, when they killed the passover, his disciples said unto him, Where wilt thou that we go and prepare that thou mayest eat the passover?
10

And Judas Iscariot, one of the twelve, went unto the chief priests, to betray him unto them.

11

And when they heard it, they were glad, and promised to give him money. And he sought how he might conveniently betray him.

12

And the first day of unleavened bread, when they killed the passover, his disciples said unto him, Where wilt thou that we go and prepare that thou mayest eat the passover?

13

And he sendeth forth two of his disciples, and saith unto them, Go ye into the city, and there shall meet you a man bearing a pitcher of water: follow him.

14

And wheresoever he shall go in, say ye to the goodman of the house, The Master saith, Where is the guestchamber, where I shall eat the passover with my disciples?

Counter-Arguments

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

First Day of the Week

The verse explicitly mentions "the first day of unleavened bread," which is a specific day in the Jewish calendar, not "the first day of the week."