How does God come in between a person and his heart, and when does that happen?

Allah Almighty intervenes between a person and their heart by preventing them from certain things He does not wish for them. Thus, He intervenes between a believer and disbelief and sins, between a disbeliever and faith, and between a person and some of their desires. Indeed, Muslim narrated from Abdullah ibn Amr ibn al-Aas that the Prophet, peace be upon him, said: "Verily, the hearts of all the children of Adam are between two fingers of the Most Merciful as if they were one heart. He turns them as He wills." Then the Messenger of Allah, peace be upon him, said: "O Turner of the hearts, turn our hearts to Your obedience." Ibn Abbas, regarding the verse: (And know that Allah intervenes between a person and their heart), mentioned that He intervenes between a believer and the sin that would lead them to Hellfire, and between a believer and disbelief, and between a disbeliever and faith. Ibn Mas'ud said: "Indeed, a servant may intend to pursue a matter of trade or leadership until it is made easy for him, then Allah looks at him and says to the angels: 'Turn him away from it, for if I make it easy for him, I will admit him to the Fire.' So, Allah turns him away from it." There is no specific time for this, for Allah's action is not limited by time; He does what He wills whenever He wills.