First, customary ablution was done upon the guest entering a house and before a meal.  This was the sequence of events in Genesis 18:1-5 when Abraham received the Lord and two others by the oaks of Mamre, and in Genesis 24:32-34 when Laban received the old servant of Abraham at Nahor.  Centuries later, this was the sequence of events Jesus expected in Luke 7:36-45 when he was in the house of a Pharisees named Simon.  In contrast, the footwashing instituted by Jesus was administered midway during supper.

Second, customary ablution was done by a person of inferior status for a person of superior status.  In 1 Samuel 25:41 when the emissaries of David came to Abigail to offer her the king’s hand in marriage, she bowed down with her face to the ground and said, “Here is your maidservant, ready to serve you and wash the feet of my master’s servants.”  In the footwashing of Jesus, it was the master who washed the feet of the disciples.

Third, in John 13:6 when Jesus was about to wash Peter’s feet, the latter exclaimed in shock: “Lord, are you going to wash my feet?”  In John 13:8 he even vehemently refused it: “Never shall you wash my feet!”  Peter was a Jew living among Jews in the land of the Jews.  He couldn’t have been ignorant of Jewish customs.  If Jesus were just performing Jewish customary ablution, why the exclamation of shock and vehement refusal?  The reaction of Peter confirms that Jesus was doing something out of the ordinary.  A Jewish customary ablution was as ordinary as could be.  Moreover, if all that had transpired was merely Jewish customary ablution, it is baffling why in John 13:7 Jesus would say to a Jew like Peter, “What I do you do not realize now, but you will understand hereafter.”  Why couldn’t Peter, a Jew, understand Jewish customary ablution?