What will happen to a person who commits the same sin again and again?

The repeated sin of a disobedient person is forgiven if each sin is followed by sincere repentance. Sincere repentance is accepted, even if repeated, just as Abu Bakr accepted the repentance of the apostates who disbelieved, then embraced Islam, then apostatized again, then embraced Islam.

Repentance must be sincere and not merely a pretense. This does not mean encouraging sins, but rather encouraging the disobedient to repent, for the door of Allah is open and His forgiveness is immense. Therefore, a servant should not despair of Allah's mercy.

The hadith (definition) qudsi confirms that Allah forgives His servant whenever he sins and repents to Him. Allah knows that a servant may sin and return to sin, yet He forgives him as long as he knows that he has a Lord who forgives sins.

Ali ibn Abi Talib said: "The best among you is every tempted repenter." If he returns [to sin], let him seek forgiveness and repent so that Satan is the one who is defeated, because "the one who repents from sin is like one who has no sin."

Al-Hasan (definition) al-Basri also said: "Satan would love to gain this from you, so do not tire of seeking forgiveness." He also said: "I see this as nothing but the morals of believers."

Umar ibn Abd al-Aziz said: "O people, whoever commits a sin, let him seek Allah's forgiveness and repent. If he returns [to sin], let him seek Allah's forgiveness and repent... for destruction lies in persisting in them."

A servant inevitably commits the sins that have been decreed upon him, but Allah has provided him an escape through repentance and seeking forgiveness. Whoever repents is freed from the evil of sins, and whoever persists perishes.