What is the expiation if I smoked cigarettes after having sworn: "By God Almighty, I will not smoke cigarettes again, and if I do, then you [my wife] are to me as my mother"?

If a man swears on the Qur’an that he will not smoke cigarettes, and tells his wife, “You are forbidden to me like my mother and sister if I smoke,” then he breaks his oath, he must repent and offer expiation for breaking an oath.

As for his statement to his wife, its ruling is that of ẓihār (a pre-Islamic form of divorce), and he must offer expiation for ẓihār by fasting for two consecutive months. If he is unable to do so, then he must feed sixty poor persons.