A hymn, mentioned as chief of the Vedas (chandato mukham) (SN.vs.568). It consists of three lines of twenty four letters (tipadam catuvísakkharam) (SN.vs.457).
The Commentary (SNA.ii.403) explains that the latter refers to the Ariya Sávitti, which consists of the formula "Buddham-, Dhammam-, Sangham- saranam gacchámi."