What is the ruling on one who swore an oath to Allah upon the Qur'an to quit smoking, then broke it, and repeated that?

If the covenant is in the form of an oath, such as "By Allah's covenant, I will not smoke," then it is an oath that necessitates an expiation upon breaking it, especially if it was sworn upon the Qur'an. However, if it is merely a pledge without an oath, then it does not necessitate the expiation of an oath, but it is considered a heinous sin.