Choral work for 3 equal voices a cappella, music by César Geoffray (1901-1972), text by Saint Francis of Assisi (1182-1226) , adapted by Léon Chancerel.
Also sometimes named : "Le chant d'Assise" (Song of Assisi).
An example of performance by belgian women choir Fugato, conductor Marie-Claude Remy (2014) :
Partition Chant Choral trois Voix Égales - SSA a cappella