After Jesus is anointed at Bethany and Judas offers to betray him, Jesus instructs his disciples to prepare for the Passover meal. Matthew 26:17-19 is a summary of Mark 14:12-16. Matthew omits the sign (a man carrying a jug) and he does not describe the room as a large, upper room, or a “guest” room.
The first day of Unleavened Bread refers to the first day of a seven-day festival starting on Nisan 15, beginning with the Passover meal on the evening of Nisan 15. Based on Exodus 12:18, on Nisan 14 a family would dispose of all the leaven in the house. The first meal eaten with unleavened bread is the Passover meal. This explains the tradition of matzah crackers at Passover. Matzah made of flour and water. In Sephardic tradition allows for eggs in the mix; Ashkenazi forbid eggs. The flour must be from one of the five grains: wheat, barley, spelt, rye or oat. There are many variations on this recipe among different Jewish communities.
In the context of the first Passover, The Israelites left Egypt so quickly they could not wait for bread to rise, so they ate unleavened bread. Sometimes matzah is called “poor man’s bread,” so it reminds the Jews of their slavery in Egypt, the “bread of affliction” (Deut 16:3).
Jesus has a disciple in Jerusalem who allows Jesus and his disciples to use a room in his house (26:17-18) The Greek word δεῖνα means “a certain man,” a person the speaker does not wish to name (BDAG; used only here). Jesus identifies himself as the teacher, and that his time is at hand.
Who is this unnamed disciple? A (possibly) wealthy disciple who owns a house in Jerusalem with a room large enough for at least thirteen men to eat. This implies cooking area and people to prepare and serve the meal (although this could be done by the disciples themselves along with Jesus’s female followers). Oddly, this unknown disciple is not mentioned again (was he not invited to the Passover meal he was hosting?) Did Jesus have any wealthy followers in Jerusalem? John suggests both Joseph of Arimathea and Nicodemus were both members of the Sanhedrin. Joseph owned a tomb near the city, which may indicate wealth. The linen they used to prepare Jesus’s body was costly and seventy-five pounds of spices was a very expensive burial gift (John 19:38-42).
In Mark, the location is called an “upper room,” although Matthew just refers to a house (ESV, the word does not appear in Greek; πρὸς σὲ “with you.” Nolland has “at your place” (Matthew, 1064). Since the traditional location of the upper room is near several large homes from the first century, it is possible the room is a large space used for storage in a mansion-like home. (See here for the mansions possibly belonging to the high priests Caiaphas and Annas.)
The traditional location of the upper room is near the Zion Gate, near the Tomb of David. Although the location shown to tourists is certainly not the upper room (it is an old mosque abandoned after the six-day war), the area has many large homes (both suggested locations for Caiaphas’s home is not far; proximity to David’s Tomb fits well with Peter’s sermon in Acts 2).
With the meal prepared, Jesus predicts two betrayals, with the sign of the bread and wine between.