The Ruling on carrying Cigarettes in Prayer

Question :

I observe that some people enter the mosque to pray while they are carrying cigarettes in their pockets. Are they committing any sin by doing this?

Answer:

They are not committing any sin regarding the prayer by carrying these cigarettes, because carrying them does not affect the prayer, since cigarettes are clean, not physically impure. But he is guilty of a sin in smoking these cigarettes, because it has become apparent in our time that smoking is forbidden, even though scholars of earlier times may have differed regarding its ruling, some of them allowing it, and some of them declaring it detestable, while others forbade it. But after it was confirmed from the medical viewpoint that it is harmful and that it causes a person to be afflicted with incurable diseases which lead to death, it became clear that it is forbidden, based upon the Words of Allah, the Most High:
And do not throw yourselves into destruction.

It has been authentically reported from the Messenger of Allah that he forbade eating onions and garlic before going to the mosque, and he said that it is harmful and the angels are harmed by what harms mankind; and when we look at smoking, we find that its smoke is harmful to the body, and that it causes loss of wealth and annoys the people.

Source:
Ibn 'Uthaimin
Fatawa Islamiyah, Vol. 2 Pages 216-217