A person observing Itikaf is not allowed to smoke cigarettes, bidis, or a hookah inside the mosque. In fact, the Holy Prophet ﷺ even prohibited people from coming to the mosque after eating raw onions, garlic, or anything that causes a bad smell.

(Sahih Muslim: 1136)

Meaning: Hazrat Ibn Umar (RA) reported that the Messenger of Allah ﷺ said: Whoever eats this plant (garlic) should not come near our mosque until the smell has disappeared from his mouth.