Nasir al-Din al-Tusi
Nasir al-Din al-Tusi has said that the infallibility of the Imam does not exclude the capacity to commit sins. Allamah Majlesi says that through reason and intellect, steadfastness in prayer and fasting, and by God's guidance, a person can reach a state where there is no desire except God's desire, and, because of an excessive love of God, shame in committing sin.