John 12 opens with Jesus having his feet washed and anointed by Mary the sister of Martha and Lazarus, despite the objections of Judas Iscariot.
John 13 opens with Jesus washing his disciples’ feet, despite the objections of Peter. (Although Peter to his credit attempts to opt for feet, hands, and head once Jesus hints at the significance of the act.)
Jesus Washing Peter’s Feet by Ford Madox Brown, circa 1856
These two events both point to Jesus’ impending death, but in starkly differing ways.
Mary’s anointing of Jesus’ feet directly prefigures his burial, and Jesus says as much in his (relatively mild) rebuke of Judas: “Leave her alone, so that she may keep it for the day of my burial…”
Jesus’ washing his disciples’ feet is arguably a much bigger deal. Here he is demonstrating to them that his looming sacrifice is something that they cannot earn. They must undergo a profound metanoia in order to understand this completely surprising fact that turns the logic of the world upside down, and is the very essence of the gospel.