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