Is it true that a person's voicing of their fears and thoughts can be used by Satan against them, and is it true that Satan cannot know what is in a person's heart?

Only Allah Almighty knows what is in the hearts of His servants. No human, jinn, angel, or messenger can know this unless Allah reveals it to a prophet or messenger. If a person vocalizes what is in their heart, people will know it because of this declaration, but they do not possess the power to bring benefit or avert harm except by Allah's permission. The jinn have abilities that surpass humans; they see humans from where humans cannot see them. We ask Allah to protect us from the rebellious jinn and devils.