THIS MIGHT SURPRISE YOU
The answer
John, and John alone. In John 13 Jesus gets up from supper, takes off his outer robe, ties a towel around himself, pours water into a basin and washes the disciples' feet. Matthew, Mark and Luke tell the supper without the foot washing, and John tells the supper without the bread and the cup.
Why it’s interesting
Washing someone's feet was typically a slave's job, or a job a student did for his teacher. The towel was what a slave wore. Peter's first words when Jesus reaches him are "Lord, are you going to wash my feet?"
Scholarly consensus
Learn the Bible.
Not just the stories, but the history, authorship, and scholarship behind it.