“The Last Supper and the Timing of Passover,” by Eric D. Huntsman, at BYU New Testament Commentary
“While the synoptic Gospels (Matthew, Mark, and Luke) identify the Last Supper as a Passover meal, the Gospel of John maintains that the Last Supper was the night before the Passover meal. Efforts have been made to resolve this discrepancy, appealing to the possible use of different calendars by the various Jewish groups that existed in the first century A.D. In the end, however, suspending judgment on which is ‘correct’ and looking separately at symbolic and theological intents of the different gospels seems like the best approach.”
“The Lost Commandments: The Sacred Rites of Hospitality,” Peter J. Sorensen, BYU Studies, Vol. 44, no. 1
Being a good host is a form of unconditional love. Just as one cannot wholly merit mercy (for the very essence of mercy is that the recipient is unworthy of it), so one clearly cannot be a partial host, catering only to visitors who meet preconceived qualifications.
At the Last Supper, Jesus is the host. It is fortunate that John 13 preserves the scene of the Last Supper that is missing from the synoptic gospels. Peter’s hesitation to let Jesus wash his feet stems not from a wanton ignorance of hospitality, but from his high regard for Jesus’ place and mission; once Peter realizes the ordinance has eternal or cosmic significance, he rushes headlong to be washed head to foot—a remarkably resonant comment about higher ordinances.