Medical science has concrete proof that smoking cigarette causes sever self-destruction. And Allah (SWT) says in the Qur’an:
[Surah Baqara 2:195]
And spend in the way of Allah and do not throw [yourselves] with your [own] hands into destruction [by refraining]. And do good; indeed, Allah loves the doers of good.
Therefore, it is clearly prohibited (meaning haraam).
On the other hand, cigarette is proved to have no valid utility or benefit, thus it is a wasteful expenditure. And Allah (SWT) says in the Qur’an:
[Surah Bani Israel 17:26-27]
And give the relative his right, and [also] the poor and the traveler, and do not spend wastefully. Indeed, the wasteful are brothers of the devils, and ever has Satan been to his Lord ungrateful.
Therefore, it is both ways prohibited (meaning haraam).
For more detail:
http://islamgreatreligion.wordpress.com/2010/04/08/is-smoking-haram-in-islam/
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