The so-called Mandatum ceremony on Maundy Thursday, the Washing of the Feet, based on the narrative in the Gospel of John 13: 1-17, was considered – by Karl Young and his followers – to be a liturgical ceremony which ‘could have’ been turned into a drama, but did not. In a modern discourse where the notion of ‘liturgical drama’ is no longer generally accepted to refer to a well-defined medieval phenomenon, the ceremony needs a new discussion as a part of the celebrations on Maundy Thursday with special representational features. In this paper, and based on a newly discovered ceremony in an eleventh-century Aquitanian fragment, I intend to discuss this ceremony, liturgically, musically as well as in relation to the biblical text at its basis.