Cyclopedia of Biblical, Theological and Ecclesiastical Literature
(rehearsal of the creed). In early times the candidates for baptism were accustomed, on Maundy-Thursday, to recite publicly the creed in the presence of the bishop or presbyters, and this act was designated redditio symboli.
These files are public domain.
McClintock, John. Strong, James. Entry for 'Redditio Symboli'. Cyclopedia of Biblical, Theological and Ecclesiastical Literature. https://www.studylight.org/encyclopedias/eng/tce/r/redditio-symboli.html. Harper & Brothers. New York. 1870.