Question: I saw a man who was reciting the Quran and there was gum in his mouth. What is the ruling on that? If he ate leeks after the isha prayer and says: “that the time [between ‘Isha and Fajr] is long and I also use a toothbrush and toothpaste before the Fajr prayer. [However], the gum decreases the scent [of the leeks] and I eat it as [a form of] medicine because the doctors have said that gum cleans the stomach”? So benefit us, may Allah reward you with good.
Answer: “First, I do not think he can establish the letters [of the Quran] if he recites and he is chewing gum. This is because the exiting points of the letters (مخارج ) will be preoccupied with chewing the gum. And it is well-known that it is not allowed for a person to recite the Quran, except if he makes the letters apparent [during the recitation of the Quran] to the best of his ability. If he wants to recite the Quran, then let him leave off the gum…”
[Liqaa Bab al-Maftooh no. 148]
Faisal Ibn Abdul Qaadir Ibn Hassan