What is the ruling on one who swore upon the Qur'an, by placing his hand upon it, that he would not return to smoking or fornication, and then returned to both?

It is not permissible for a Muslim to commit forbidden acts. Swearing an oath upon the Qur’an to abandon them further emphasizes the oath. If one returns to them after swearing such an oath, repentance is obligatory, along with an expiation for the oath: feeding ten poor persons, or clothing them, or freeing a slave. If unable to do so, one must fast for three days. Smoking and adultery are among the forbidden acts.