How can one cast out the devil both outside of prayer and within it?

Satan is driven away by seeking refuge in Allah from his whisperings, as Allah Almighty said: (And say, "My Lord, I seek refuge in You from the incitements of the devils, And I seek refuge in You, my Lord, lest they be present with me.") And when two men reviled each other, the Prophet, peace and blessings be upon him, said: "Indeed, I know a word which, if he were to say it, what he finds would depart from him. If he were to say: 'I seek refuge in Allah from Satan, the accursed,' what he finds would depart from him." In prayer, if you feel the whispering of Satan, who is called "Khanzab," then seek refuge in Allah from him and spit to your left three times. It is also necessary to ponder what is recited and to perfect purification; for it is a great gateway to the servant's humility in his prayer.