John13chapter 13

Foot washing was the lowest task in a household. Roads were dust or mud, people wore open sandals, and a guest's feet were washed on arrival — by a slave, and specifically by a non-Jewish slave where one was available, since Jewish teaching held that a Hebrew slave could not be required to do it. That is the job Jesus took, stripped down and with a towel round his waist, and it is why Peter refuses.

The seating explains how the evening works. Guests reclined on their left sides around a low table, feet outward, so the person to your right had his head near your chest and could speak to you without being overheard. It also explains how someone could reach the feet of every guest without anyone standing up.

Handing a dipped morsel to a guest was a mark of honour, the host singling someone out. That is what makes the exchange with Judas so quiet: to everyone else at the table it looked like a courtesy, which is exactly why nobody understood what was happening when he went out.

John dates the meal in relation to Passover differently from Matthew, Mark, and Luke, who present it as the Passover meal itself, while John says the authorities the next morning avoided defilement so they could eat the Passover. Explanations offered include different calendars in use at the time, different reckonings of when a day began, and a wider use of Passover for the whole festival week. It is a genuine open question, and it is named rather than smoothed over.