Is it permissible to swear off smoking, imprecating oneself should one return to it, and what should one who has done so out of ignorance do?

Smoking is haram (forbidden). The questioner erred by cursing himself, for cursing is expulsion and banishment from Allah's mercy. Severe warnings have been reported concerning it, such as the hadith: "O company of women, give in charity, for I have been shown that you are the majority of the inhabitants of Hellfire. They asked, 'And why, O Messenger of Allah?' He said, 'You curse frequently and are ungrateful to your husbands,'" and the hadith: "Indeed, those who frequently curse will not be witnesses or intercessors on the Day of Resurrection." If the questioner returns to smoking, he incurs sin and must repent and offer an expiation for breaking an oath, which is feeding ten poor people, or clothing them, or freeing a slave. If he is unable to do so, then fasting for three days.