He wants to give up smoking; can he swear an oath concerning himself?
Question

                Is it permissible for a smoker to swear by Allaah that he will not smoke, and say “May the curse of Allaah be on me if I go back to smoking”? Because he cannot find any other means of making himself give it up. Or is this wrongful speech?
Praise be to Allah.We put this question to Shaykh Muhammad ibn Saalih 
          al-‘Uthaymeen, may Allaah preserve him, who answered as follows: 
  He should not swear an oath to give up 
          smoking, or pray for himself to be cursed. Allaah says (interpretation 
          of the meaning): 
“They swear by Allaah their strongest oaths, that if only you 
          would order them, they would leave (their homes for fighting in Allaah’s 
          Cause). Say: 
          ‘Swear you not; (this) obedience (of yours) is known (to be false). Verily, 
          Allaah knows well what you do.’” [al-Noor 24:53] 
Question: But this [aayah] 
          has to do with the munaafiqeen (hypocrites), and our friend is sincere.
  Answer: This [ayah] is general [in meaning]. Every person who 
          wants to worship Allaah should not swear an oath concerning his worship; 
          let him strive of his own free will, not under compulsion. 
  Question: so this way is wrong and he will be sinning if he does 
          it? 
  Answer: No, what is denounceable is the fact that he is trying 
          to confirm something through this oath. 
  Question: So we can say that this is an action which is not prescribed 
          in Islam? 
Answer: Yes, undoubtedly. And Allaah knows best.