Do the hateful whispers and doubts that occurred, despite a motivation to reject disbelief, constitute disbelief?

This story is false and not found in Sahih al-Bukhari. Disbelief does not occur due to whispers as long as the person dislikes them. It is advised to turn away from indulging in these whispers with Satan and to occupy oneself with learning and inviting to Allah, by setting a program for memorizing the Qur'an, learning fiqh, and reading books on virtues, heartwarming stories, and biographies.