The first part of the Canticle, up to the verses about pardon and peace, he composed in the garden of the Poor Clare's convent at San Damiano, where he lay sick and in intense suffering for six or seven weeks. He then composed a melody for it and frequently urged his brothers to sing it when they were out preaching. The second part, consisting of the next two verses about pardon and peace, he composed a short time later in an effort to restore peace between the quarreling parties in a dispute between the civil and religious authorities of Assisi. The final verses about Sister Death Francis added shortly before his own death, after Brother Leo and Brother Angelo had sung the Canticle at his request. Celano adds that his last words were: "Welcome, my Sister Death."
St. Francis of Assisi
Omnibus of Sources