Clearing the Throat does not invalidate the Prayer
Question :
Mave next to a mosque where I perform Zuhr, 'Asr, Maghrib and 'Isha' prayers, and just recently, when the Imam recites in the Maghrib and Isha' prayers, he clears his throat a lot therein, more than three times in each Rak'ah. Does this action invalidate the prayer or not? Inform us, may Allah bless you.
Answer:
There is no objection to prayer behind this Imam, even if he clears his throat a lot, because it does not invalidate the prayer if it is done out of necessity; and normally it does not occur in the way which you have described except due to necessity.
Source:
Ibn Jibreen
Fatawa Islamiyah, Vol. 2 Pages 247-248