11 As a youth, St. Francis was expansive and highstrung, a lover of luxurious dress. He was accustomed to invite to magnificent banquets the friends he had chosen from among the fashionable and pleasure-loving young men of the town. He walked through the streets with them, singing gaily. But even at that time in his life he became known for the integrity of his moral life, his correctness in conversation, and his utter disdain of wealth. After his imprisonment in Perugia, which was followed by a long illness, he felt himself, not without a certain sense of astonishment, completely transformed. However, as if he desired to flee from the hands of God, he went to Puglia on a military mission. On this journey he felt himself commanded by God in unmistakable terms to return to Assisi and learn there what he must do. After much wavering and many doubts, through divine inspiration and through having heard at solemn Mass that passage from the Gospels which speaks of the apostolic life, he understood at last that he, too, must live and serve Christ "according to the very words of the Holy Gospels." From that time on he undertook to unite himself to Christ alone and to make himself like unto Him in all things. In "all his efforts, public as well as private, he turned to the Cross of Our Lord, and from the moment he began to live as a soldier of Christ, the divers mysteries of the Cross shone round about him." (Thomas of Celano, Treatise on Miracles , No. 2) Truly he was a brave soldier and knight of Christ because of the nobility and generosity of his heart; wherefore to prove that neither he nor his disciples were ever to be separated from Our Lord, he always had recourse to the Gospels as to an oracle whenever he had to make a decision on any matter. The rules of the Orders founded by him were made to agree most scrupulously with the Gospels, and the religious life of his followers with the life of the Apostles. For this reason at the very beginning of his Rule, he wrote: "This is the life and rule of the Friars Minor, to observe the holy Gospel of Our Lord Jesus Christ." (Beginning of Rule of the Friars Minor )
Source: Rite Expiatis (Vatican.va)