Praise be to Allah.
If dawn breaks and there is something in the fasting person’s mouth and he spits it out, but he does not willingly swallow any of it, then his fast is valid. Al-Nawawi (may Allaah have mercy on him) said in al-Minhaaj: If dawn breaks and there is some food in his mouth and he spits it out, his fast is valid. It says in Mughni al-Muhtaaj (2/161): Because if he put it in his mouth during the day it would not invalidate the fast, so it is more likely that this is the case if he put it in his mouth at night. But if he swallows any part of it deliberately, then he had broken his fast. End quote.
Doctors and researchers have warned against chewing tobacco, and they have stated that this is not regarded as a safe alternative to smoking; rather it is more dangerous and more harmful to the body than smoking in some ways, because it exposes the body to the risk of cancer more than smoking.
What the one who has decided to give up smoking should do is to give it up completely and seek the help of Allaah with regard to that. It has been proven by experiments and experience that it is possible to stop smoking and that giving it up is easy. What matters is to repent sincerely and have strong willpower.
We ask Allaah to help and guide us and you.
And Allaah knows best.