Does one sin who struggles against the sin of looking [at what is forbidden] but is then overcome by his desire and falls into it?

If a Muslim intentionally looks at what is forbidden, he incurs sin, even if he struggles against himself; because he did not completely restrain himself from it. He must repent of the sin, even if it recurs, for the Prophet, peace and blessings be upon him, said: "There is no believing servant but has a sin he repeatedly commits from time to time, or a sin he persists in and does not abandon until he leaves this world. Indeed, the believer is created tried, repentant, forgetful; if reminded, he remembers." And "The one who repents from sin is like one who has no sin." As for a sudden glance that a servant has no control over, it is forgiven.